Index to J.J. Smith: Enumeration of the Orchidaceae of Sumatra (publ. in Fedde, Repert. 32, 1933, 130-386). — 32 pp. stenciled. Gratis. Index to C.L. Blume: Museum Botanicum Lugduno-Batavum vol. 2 (1856-1857). — 24 pp. offset. Gratis.