cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.15468/dl.bvxp4q
title: Occurrence Download

description: A dataset containing 2 species occurrences available in GBIF matching the query:
{
 "and" : [
 "HasCoordinate is true",
 "TaxonKey is Masdevallia cerastes Luer & R.Escobar",
 "HasGeospatialIssue is false"
 ]
}

 The dataset includes 2 records from 1 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0013964-190415153152247/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.xjv5cq
title: Occurrence Download

description: A dataset containing 773 species occurrences available in GBIF matching the query:
{
 "and" : [
 "Country is Chinese Taipei",
 "HasCoordinate is true",
 "HasGeospatialIssue is false",
 "OccurrenceStatus is Present",
 "TaxonKey is Sibirionetta formosa (Georgi, 1775)"
 ]
}

 The dataset includes 773 records from 3 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0140496-200613084148143/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.ubnx4b
title: Occurrence Download

description: A dataset containing 6 species occurrences available in GBIF matching the query:
{
 "and" : [
 "Country is Tanzania, United Republic of",
 "TaxonKey is Heritiera littoralis Dryand."
 ]
}

 The dataset includes 6 records from 4 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0013964-171219132708484/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.266pxd
title: Occurrence Download

description: A dataset containing 461 species occurrences available in GBIF matching the query:
{
 "and" : [
 "Country is Korea, Republic of",
 "TaxonKey is Nemoura Latreille, 1796"
 ]
}

 The dataset includes 461 records from 11 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0261900-210914110416597/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.jzz5u9
title: Occurrence Download

description: A dataset containing 1 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Colchicum knersvlaktense (U.Müll.-Doblies & D.Müll.-Doblies) J.C.Manning & Vinn."
 ]
}

 The dataset includes 1 records from 1 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0004818-240314170635999/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.tygcon
title: Occurrence Download

description: A dataset containing 3246 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Cestrum parqui (Lam.) L'Hér."
 ]
}

 The dataset includes 3246 records from 118 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0013965-190320150433242/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.8mfpht
title: Occurrence Download

description: A dataset containing 29 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Hedychium hasseltii Blume"
 ]
}

 The dataset includes 29 records from 6 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0114422-200613084148143/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.u8wn38
title: Occurrence Download

description: A dataset containing 4 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Viola breviflora Jungsim Lee & M.Kim"
 ]
}

 The dataset includes 4 records from 2 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0136631-240321170329656/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.u9reu9
title: Occurrence Download

description: A dataset containing 184 species occurrences available in GBIF matching the query:
{
 "and" : [
 {
 "and" : [
 "HasGeospatialIssue is false",
 "HasCoordinate is true",
 "OccurrenceStatus is Present",
 {
 "not" : {
 "BasisOfRecord" : [
 "is one of (Fossil, Living Specimen)"
 ]
 }
 }
 ]
 },
 "TaxonKey is Meliphacator provocator (E.L.Layard, 1875)"
 ]
}

 The dataset includes 184 records from 8 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0004808-240314170635999/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.8jvpaz
title: Occurrence Download

description: A dataset containing 8 species occurrences available in GBIF matching the query:
{
 "and" : [
 "DatasetKey is Zariquiey Marine Crustacean Legacy Collection. CBMR-Zariquiey (ICM-CSIC)",
 "TaxonKey is Munida rutllanti Zariquiey Álvarez, 1952"
 ]
}

 The dataset includes 8 records from 1 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0013967-180131172636756/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.f2ab8n
title: Occurrence Download

description: A dataset containing 14 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Vrydagzynea micronesiaca Schltr."
 ]
}

 The dataset includes 14 records from 3 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0136633-240321170329656/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.8v3vzj
title: Occurrence Download

description: A dataset containing 21 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Zeuxine plantaginea (Rchb.f.) Benth. & Hook.f. ex Drake"
 ]
}

 The dataset includes 21 records from 7 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0136630-240321170329656/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.nh3dac
title: Occurrence Download

description: A dataset containing 12 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Acalypha hutchinsonii Britton"
 ]
}

 The dataset includes 12 records from 5 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0136632-240321170329656/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.d48fut
title: Occurrence Download

description: A dataset containing 13211 species occurrences available in GBIF matching the query:
{
 "and" : [
 "BasisOfRecord is Specimen",
 "Geometry POLYGON((12.72172 46.58659,11.28829 50.88689,-67.90891 43.36136,-96.57758 63.42943,-126.67968 49.81181,-129.54655 39.77778,-107.32833 17.2012,-89.41041 9.31732,-83.67668 -5.37538,-61.81682 -31.89389,-40.31532 -25.44344,-35.65666 -13.25926,12.72172 46.58659))",
 "HasCoordinate is true",
 "HasGeospatialIssue is false",
 "OccurrenceStatus is Present",
 "TaxonKey is one of (Sylvilagus floridanus (J.A.Allen, 1890), Sylvilagus audubonii (Baird, 1858), Sylvilagus nuttallii (Bachman, 1837), Sylvilagus bachmani (Waterhouse, 1839), Sylvilagus cunicularius (Waterhouse, 1848), Sylvilagus palustris (Bachman, 1837), Sylvilagus brasiliensis (Linnaeus, 1758), Sylvilagus mansuetus Nelson, 1907, Sylvilagus fulvescens J.A.Allen, 1912, Sylvilagus robustus (Bailey, 1905), Sylvilagus andinus (Thomas, 1897), Sylvilagus graysoni (J.A.Allen, 1877), Sylvilagus gabbi (J.A.Allen, 1877), Sylvilagus transitionalis (Bangs, 1895), Sylvilagus tapetillus Thomas, 1913)"
 ]
}

 The dataset includes 13211 records from 129 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0136629-240321170329656/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.hj64fv
title: Occurrence Download

description: A dataset containing 5841 species occurrences available in GBIF matching the query:
{
 "and" : [
 "CoordinateUncertaintyInMeters 0.0-10000.0",
 "HasCoordinate is true",
 "HasGeospatialIssue is false",
 "TaxonKey is Bison bison (Linnaeus, 1758)"
 ]
}

 The dataset includes 5841 records from 30 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0114434-200613084148143/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.qbk5yf
title: Occurrence Download

description: A dataset containing 18 species occurrences available in GBIF matching the query:
{
 "and" : [
 {
 "and" : [
 "HasGeospatialIssue is false",
 "HasCoordinate is true",
 "OccurrenceStatus is Present",
 {
 "not" : {
 "BasisOfRecord" : [
 "is one of (Fossil, Living Specimen)"
 ]
 }
 }
 ]
 },
 "TaxonKey is Eunymphicus cornutus uvaeensis (E.L.Layard & E.L.C.Layard, 1882)"
 ]
}

 The dataset includes 18 records from 6 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0004834-240314170635999/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.ofk3s0
title: Occurrence Download

description: A dataset containing 2075 species occurrences available in GBIF matching the query:
{
 "and" : [
 {
 "or" : [
 "TaxonKey is Lapsana communis subsp. adenophora (Boiss.) Rech.fil.",
 "TaxonKey is Lapsana communis subsp. intermedia (M.Bieb.) Hayek",
 "TaxonKey is Lapsanastrum apogonoides (Maxim.) Pak & K.Bremer",
 "TaxonKey is Laricobius erichsoni Rosenhauer, 1846",
 "TaxonKey is Lariophagus distinguendus (Förster, 1841)",
 "TaxonKey is Larix ×marschlinsii Coaz"
 ]
 },
 "HasCoordinate is true",
 "HasGeospatialIssue is false"
 ]
}

 The dataset includes 2075 records from 91 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0013967-180508205500799/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.hsoogt
title: Occurrence Download

description: A dataset containing 2395 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Heuchera rubescens Torr."
 ]
}

 The dataset includes 2395 records from 65 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0013967-190320150433242/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.q7vdee
title: Occurrence Download

description: A dataset containing 8 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Colchicum lagotum K.Perss."
 ]
}

 The dataset includes 8 records from 3 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0004843-240314170635999/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.bfvg4g
title: Occurrence Download

description: A dataset containing 7 species occurrences available in GBIF matching the query:
{
 "and" : [
 "TaxonKey is Pohlia wahlenbergii (F.Weber & D.Mohr) A.L.Andrews",
 "HasCoordinate is true",
 "Country is Iceland",
 "HasGeospatialIssue is false",
 "Year is greater than or equal to 2000",
 "CoordinateUncertaintyInMeters is less than 10000"
 ]
}

 The dataset includes 7 records from 2 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0136634-240321170329656/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.8skshj
title: Occurrence Download

description: A dataset containing 22 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Cochlearia tatrae Borbás"
 ]
}

 The dataset includes 22 records from 12 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0004985-240314170635999/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.b4jfwl
title: Occurrence Download

description: A dataset containing 19 species occurrences available in GBIF matching the query:
{
 "and" : [
 "Country is Colombia",
 "TaxonKey is Eusmilia fastigiata (Pallas, 1766)"
 ]
}

 The dataset includes 19 records from 7 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0013968-180824113759888/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.6xskmn
title: Occurrence Download

description: A dataset containing 4823 species occurrences available in GBIF matching the query:
{
 "and" : [
 "DatasetKey is CardObs : Observations naturalistes issues de l'outil CardObs-Données naturalistes de Pierre NOEL (pnoel)"
 ]
}

 The dataset includes 4823 records from 1 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0346213-200613084148143/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.x6shcv
title: Occurrence Download

description: A dataset containing 2395 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Heuchera rubescens Torr."
 ]
}

 The dataset includes 2395 records from 65 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0013968-190320150433242/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.gmmy8f
title: Occurrence Download

description: A dataset containing 136 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Microphis retzii (Bleeker, 1856)"
 ]
}

 The dataset includes 136 records from 21 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0346205-200613084148143/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.zgm4bu
title: Occurrence Download

description: A dataset containing 182347 species occurrences available in GBIF matching the query:
{
 "and" : [
 "BasisOfRecord is one of (Human Observation, Specimen)",
 "Country is one of (United States of America, Canada)",
 "MediaType is Image",
 "TaxonKey is Danaus plexippus (Linnaeus, 1758)",
 "Year 1899-2024"
 ]
}

 The dataset includes 182347 records from 30 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0004514-240314170635999/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.fh51v2
title: Occurrence Download

description: A dataset containing 5 species occurrences available in GBIF matching the query:
{
 "and" : [
 "Country is Colombia",
 "HasCoordinate is true",
 "TaxonKey is Masdevallia elephanticeps Rchb.f. & Warsz.",
 "HasGeospatialIssue is false"
 ]
}

 The dataset includes 5 records from 3 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0013968-190415153152247/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.y3w5sb
title: Occurrence Download

description: A dataset containing 7842 species occurrences available in GBIF matching the query:
{
 "and" : [
 {
 "and" : [
 "HasGeospatialIssue is false",
 "HasCoordinate is true",
 "OccurrenceStatus is Present",
 {
 "not" : {
 "BasisOfRecord" : [
 "is one of (Fossil, Living Specimen)"
 ]
 }
 }
 ]
 },
 "TaxonKey is Leucocarbo chalconotus (G.R.Gray, 1845)"
 ]
}

 The dataset includes 7842 records from 15 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0004826-240314170635999/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.lq0ugt
title: Occurrence Download

description: A dataset containing 8574 species occurrences available in GBIF matching the query:
{
 "and" : [
 {
 "or" : [
 "TaxonKey is Larix gmelinii (Rupr.) Kuzen.",
 "TaxonKey is Larix gmelinii var. olgensis (A.Henry) Ostenf. & Syrach",
 "TaxonKey is Larix kaempferi (Lamb.) Carrière"
 ]
 },
 "HasCoordinate is true",
 "HasGeospatialIssue is false"
 ]
}

 The dataset includes 8574 records from 156 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0013969-180508205500799/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.jh445c
title: Occurrence Download

description: A dataset containing 2399118 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Turdus pilaris Linnaeus, 1758"
 ]
}

 The dataset includes 2399118 records from 1926 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0004829-240314170635999/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.wt3ta4
title: Occurrence Download

description: A dataset containing 5336 species occurrences available in GBIF matching the query:
{
 "and" : [
 "HasCoordinate is true",
 "TaxonKey is Mikania micrantha Kunth",
 "HasGeospatialIssue is false"
 ]
}

 The dataset includes 5336 records from 174 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0024300-200613084148143/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.fouayp
title: Occurrence Download

description: A dataset containing 3 species occurrences available in GBIF matching the query:
{
 "and" : [
 "Geometry POLYGON((93.95590 22.69479,128.04410 22.69479,128.04410 36.30521,93.95590 36.30521,93.95590 22.69479))",
 "HasCoordinate is true",
 "TaxonKey is Corylus kweichowensis Hu",
 "HasGeospatialIssue is false"
 ]
}

 The dataset includes 3 records from 1 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0012066-200127171203522/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.82hace
title: Occurrence Download

description: A dataset containing 20 species occurrences available in GBIF matching the query:
{
 "and" : [
 "Continent is Africa",
 "TaxonKey is Allium cepa L."
 ]
}

 The dataset includes 20 records from 7 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0038750-210914110416597/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.rhq3vz
title: Occurrence Download

description: A dataset containing 48 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Nephrolepis cordifolia var. pumicicola (F.Ballard) Hovenkamp & Miyam."
 ]
}

 The dataset includes 48 records from 9 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0003352-200221144449610/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.8jdf9u
title: Occurrence Download

description: A dataset containing 621 species occurrences available in GBIF matching the query:
{
 "and" : [
 "HasCoordinate is true",
 "TaxonKey is Manihot peruviana Müll.Arg.",
 "HasGeospatialIssue is false"
 ]
}

 The dataset includes 621 records from 15 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0018812-200613084148143/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.6qpn5u
title: Occurrence Download

description: A dataset containing 1531 species occurrences available in GBIF matching the query:
{
 "and" : [
 "TaxonKey is one of (Alopochen aegyptiaca (Linnaeus, 1766))",
 "HasCoordinate is true",
 "Country is Belgium",
 "Year is 2003"
 ]
}

 The dataset includes 1531 records from 5 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0012069-200613084148143/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.5uf8w3
title: Occurrence Download

description: A dataset containing 617399 species occurrences available in GBIF matching the query:
{
 "and" : [
 "BasisOfRecord is Human Observation",
 "HasCoordinate is true",
 "HasGeospatialIssue is false",
 "TaxonKey is Capreolus Gray, 1821"
 ]
}

 The dataset includes 617399 records from 807 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0282144-200613084148143/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.mk9qvu
title: Occurrence Download

description: A dataset containing 279414 species occurrences available in GBIF matching the query:
{
 "and" : [
 "BasisOfRecord is Human Observation",
 "HasCoordinate is true",
 "TaxonKey is Polypodiaceae",
 "HasGeospatialIssue is false"
 ]
}

 The dataset includes 279414 records from 439 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0023921-191105090559680/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.53twbf
title: Occurrence Download

description: A dataset containing 313980 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Rupornis magnirostris (Gmelin, 1788)"
 ]
}

 The dataset includes 313980 records from 312 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0036530-200613084148143/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.25549/pcra-c14-10540
title: Put' = Voie = [The way], no. 16 (May 1929)

description: [description english/roman)] Irregular frequency
DOI: 10.15468/dl.z5ym4c
title: Occurrence Download

description: A dataset containing 1 species occurrences available in GBIF matching the query:
{
 "and" : [
 "TaxonKey is one of (Megophrys maosonensis Bourret, 1937)",
 "BasisOfRecord is one of (Specimen, Human Observation, Observation, Machine Observation)",
 "HasCoordinate is true",
 "HasGeospatialIssue is false"
 ]
}

 The dataset includes 1 records from 1 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0067177-230224095556074/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.15468/dl.zc69e9
title: Occurrence Download

description: A dataset containing 931 species occurrences available in GBIF matching the query:
{
 "TaxonKey" : [
 "is Telmatherina bonti Weber & de Beaufort, 1922"
 ]
}

 The dataset includes 931 records from 8 constituent datasets; see https://api.gbif.org/v1/occurrence/download/0337890-210914110416597/datasets/export for details.
 
Data from some individual datasets included in this download may be licensed under less restrictive terms.
DOI: 10.25549/pcra-c14-9237
title: Put' = Voie = [The way], no. 6 (January 1927)

description: [description english/roman)] Irregular frequency