> my question is ... Can be a good start point for a NetBSD fan. ? or i
> need a more detailed book.

The canonical example was always "The Design and Implementation of the
4.4 BSD Operating System".

    http://www.awprofessional.com/title/0201549794

Obviously some of this has been overtaken by developments in NetBSD,
but it is still a very good read.  The equivalent book for SVR4 is
"The Magic Garden Explained".

    http://www.amazon.com/exec/obidos/ASIN/0130981389/104-7798500-5471162

Also worth reading is "UNIX Internals: The New Frontiers".

    http://www.amazon.com/exec/obidos/ASIN/0131019082/104-7798500-5471162

At least, those are my top kernel books.

Cheers,
Rob