de Vogel, E.F. 1969. Monograph of the tribe Apostasieae. Blumea 17: 313-350.
Pridgeon, A. M., P.J. Cribb, M.W. Chase & F.N. Rasmussen (Eds.). 1999. Genera Orchidacearum, Volume 1: General introduction, Apostasioideae, Cypripedioidae. Oxford University Press, Oxford.