http://www.pbs.org/wgbh/evolution/educators/lessons/lesson2/2_worldmap.pdf
http://www.galapagos.to/TEXTS/DIARY.HTM
http://www2.lucidcafe.com/lucidcafe/library/96feb/darwin.html
http://pages.britishlibrary.net/charles.darwin
http://www.nieuwezijds.nl/lees-darwin-nu/downloads.php
via DELTA ANW Synthese eerste druk, 3e oplage, ISBN nummer:9023839439