Home›Browse›sunflower🌐EnglishEnglishDeutschEspañolFrançaisPolskiTiếng Việt한국어日本語EntityQ423986· pop 9· linked from 12 articlessunflowerSign in to saveAlso known as Δ-systemcollection of sets in which every two sets have the same intersectionAvailable in 9 languagesEspañolFrançaisDeutsch日本語HungarianPolskiTiếng Việt한국어via Wikidata sitelinks · CC0