SZELĄG, ZBIGNIEW. “<em>Hieracium umbellonigritum</Em> (Asteraceae), a New Hybridogenous Species from the Sudetes in Poland”. Phytotaxa 589, no. 3 (March 28, 2023): 289–292. Accessed March 14, 2025. https://phytotaxa.mapress.com/pt/article/view/phytotaxa.589.3.8.