Verbascum humile subsp. tzar-borisii Stoj. in Izv. Tsarsk. Prir. Inst. Sofiya 1: 144. 1928
Verbascum humile subsp. tzar-borisii in Izv. Tsarsk. Prir. Inst. Sofiya 1: 144. 1928
is basionym for Verbascum tzar-borisii, Fl. Republ. Bulgariya 10: 50. 1995
Verbascum humile subsp. tzar-borisii in Izv. Tsarsk. Prir. Inst. Sofiya 1: 144. 1928