Photographs from the Siboga expedition can be found in the Tropenmuseum, the Special Collections of the University of Amsterdam and the Artis Bibliotheek, at the same university.
ref: Allard Pierson, Artis library, University of Amsterdam, Artis 300.047
https://commons.wikimedia.org/wiki/File:UvA-Artis_300.048_-_Siboga_-_Lamakera_op_Solor.jpg
Copyright: Public Domain