English: According to the colophon of the book the copyright holder was P. A. van de Stadt. He died in 1940, so the copyright will have been transferred to the descendants of Van de Stadt. I contacted two grandchildren, H. A. N. Versluys en H. P. van de Stadt, the latter being considered the main inheritor of the family (a remaining copy of the book was transferred to him for that reason) and got permission to publish any part of the book as I saw fit. However, since other descendants that I have not been able to locate may also be around, and since neither H. A. N. Versluys nor H. P. van de Stadt knew of any formal document taking care of the transference of the copyright of the book, copyright may be shared among them and other dispersed still remaining family members. For that reason, the book may be non-free till 2010. In this instance (the use of a picture of the title-page as an illustration to go with a discussion of the book itself and biographical information of the compiler (his portrait being on the title-page) we should be able to use the picture of the page under fair use till 2010, while after that date it will be in the public domain. --Kornelis 06:39, 2 May 2007 (UTC)