Studies in the Gentianaceae: Gentiana, Section Pneumonanthe, subsection Angustifoliae.
Clausen, Robert T.
Studies in the Gentianaceae: Gentiana, Section Pneumonanthe, subsection Angustifoliae. - U.S.A. 1941.
Studies in the Gentianaceae: Gentiana, Section Pneumonanthe, subsection Angustifoliae. - U.S.A. 1941.