Unidentified photographer, 1899, 16 September, Siboga expedition to the Dutch East Indies. Expedition led by Max Wilhelm Carl Weber. In this photo, four members of the expedition's scientific staff are portrayed. From left to right: H.F. Nierstrasz, J.W. Huysmans, Prof. Max Weber and Dr. J. Versluys., Photograph, University of Amsterdam, Special Collections, LL/76256

Unidentified photographer, 1899, March - 1900, February, Siboga expedition to the Dutch East Indies. Expedition led by Max Wilhelm Carl Weber, Photograph, University of Amsterdam, Special Collections, LL/76257