COI00039507 - Cirsium acaule var. microcephalum - Bernal, Francisco Loscos - s.n..jpg
Botanical Society of Britain and Ireland
Portál informačního systému ochrany přírody
Herbarium of the University of Coimbra (COI)
Taxonomy database of the U.S. National Center for Biotechnology Information
Global Biodiversity Information Facility
Interim Register of Marine and Nonmarine Genera
Open Tree of Life reference taxonomy version 3.2