Some questions about a bass

[Fernando González]

The neck has the holes of previous tyrolean machines and the wood is quite different of the rest of the instrumets. As it has a clearly important reparation may be the neck isn´t the original.

How do you know about the varnish source? This is very interesting.
Is there any book, source, etc, about the bass making schools over the time and his caracteristics?

Thank you very much!!!