Canadensys: University of Alberta Vascular Plant Herbarium (ALTA-VP)
Canadensys, operated from the Université de Montréal Biodiversity Centre
"113793 - Cirsium arvense (L.) Scop. var. horridum Wimm. & Grab., University of Alberta Vascular Plant Herbarium." University of Alberta Museums Search Site, https://search.museums.ualberta.ca/12-151018. Accessed 31 May. 2025.