You can find info in the little volume "Indonesisce Schwertgriffe" (some 40 pages, mostly dedicated to mandau hilts). It s an article from "Annalen des K.K. Naturhistorischen Hofmuseum", written in Wien in 1899 by Dr Franz Steindacher.
I have found it at Aquila Natural History Books through Abebooks.
email:
aquilabooks@planet.nl. Unfortunately (for me) it is written in German. But I could enjoy the good drawings ....