CC0Crataegus irrasaresearchiNaturalist observation 98513097Open Tree of Life reference taxonomy version 3.2Charles Sprague SargentCrataegusTaxonomy database of the U.S. National Center for Biotechnology InformationGlobal Biodiversity Information FacilityThe Plant List 1.1taxonCrataegus irrasaDatabase of Vascular Plants of CanadaGRIN Taxonomy for PlantsUnited States Department of Agriculture Plants DatabaseTropicosPlants of the World OnlinespeciesWorld Flora OnlineEncyclopedia of LifeIntegrated Taxonomic Information SystemInternational Plant Names IndexiNaturalist observation 79873441iNaturalist observation 79873444