🌐EnglishEnglishDeutschEspañolFrançaisPortuguêsTiếng ViệtРусскийالعربية한국어中文日本語EntityQ1667423· pop 12· linked from 27 articlesInternational Patent Classificationhierarchical patent classification systemConnectionsInternational Standard Book NumberEntityCouncil of EuropeEntityCategoriesInternational classification systemsPatent classifications