I'm looking to buy a book on sausage making. Here is what I am looking for. . . There's almost nothing to flip through in the local book stores so I'm soliciting opinions here.

I want something basic that explains the rules and the hows and why science type stuff.
I want nitrate / nitrite free options.
I would like it to have pictures / recipes / Tips
A focus on things like salamis and italian / spanish sausages.

Does anybody have something to recommend?