van Steenis, C. G. G. J. Pacific Plant Areas 1, 121 (1963).

Hegnauer, R. Chemotaxonomie der Pflanzen 2, 432-434, 494 (Birkhäuser, 1963).

Jordanov, D. Flora Reipublicae Popularis Bulgaricae 1, 212-215 (1963).

Gleason, H. A. The new Britton and Brown Illustrated Flora of the Northeastern United States and adjacent Canada. 1, 86-88 (Hafner, 1963).