Works:
- Cypripediaceae, Orchidaceae : Orchidoideae, Tropidioideae, Spiranthoideae, Vanilloideae, Epidendroideae p.p.
- Taxonomy of Cyrtochilum-alliance (Orchidaceae) in the light of molecular and morphological data
- Orchidaceae of West-Central Africa, Vol. 3.. Vandoideae (continued)
- Orchidaceae of West-Central Africa, Vol. 2.. Epidendroideae, Vandoideae (in part)