The ftp sites in The Netherlands are at Surfnet and at the Universiteit van Amsterdam.
A tour through the source files.
How to write a device driver. An unzipped copy for easy clicking.
I wrote a page on how to configure the combination of NetBSD + XS4All + IPv6.
I also wrote a page about Soekris + NetBSD.
"Lions' Commentary on Unix: With Source Code" by John Lions
"A Quarter Century of Unix" by Peter H. Salus
"The NetBSD book" by Michael W. Lucas.