HYBRIDE [= PS. OF H.R. VAN HEEKEREN] - Voetsporen aan de kim. Vijftien jaar als amateur-natuurondezoeker in tropen.

. Batavia-Centrum, N.V. G. Kolff & Co. [c.1940]. Illustrated with b/w photographs. 123 pp. Orig. green cloth. Collection of essays written by the amateur naturalist and palae-anthropologist H.R. van Heekeren about his travels in Java and Sulawisi between 1923 and 1940; mountain trips to volcanoes in Java, palaeanthropological excavations in Java and Celebes.