Microform was a popular storage medium before there was digital storage, which allows much greater compression of data, but microform has never been popular with those who must use it to retrieve information. See also reserves P periodicals items published regularly at least twice a year. Daily and weekly newspapers, weekly news magazines, monthly hobby magazines, quarterly and semi-annual scholarly journals are common types of periodicals. See also serials periodical indexes and abstracts periodical indexes list articles which have appeared in journals, magazines, or newspapers. They list author, title, name of periodical, volume, pages and date of publication.
Abstracts are indexes that also contain summaries of the article.
Both indexes and abstracts may be in print or electronic form. Indexes and abstracts are discussed in OWL 3 . The data for each item in an electronic database makes up a record. Records are discussed in OWL 4 . Reference Collection reference materials either provide specific information such as an address, a date, or a definition, or they have overview information on a subject, or they indicate sources for more information.