Question: What thesaurus has British Museum as the smallest Wikidata property?
Paraphrase: What thesaurus has British Gallery as the littlest Wikidata property?
SPARQL (Wikidata): select ?ent where { ?ent wdt:P31 wd:Q17152639 . ?ent wdt:P3575 ?obj . ?ent wdt:P1687 wd:P3633} ORDER BY ASC(?obj)LIMIT 5