One of the smallest books in my whole BookTip section, but nevertheless a pretty informative one is this 128-page booklet by Reinhard Schmitz.
Analog Synthesis -The Newbie Guide to Synthesizers and Sound-Design (also available in German) is full of basic info on how synthesis works. Very easy to read, and focused mainly on beginners this is a nice resource for all things synth...
In different chapters the main components of a (modular) synthesizer are explained, accompanied by simple black/white pictures and graphs.
The book is completed with an extensive glossary and a pretty nice 39-track audio-CD with audio-examples of the most important analog synthesizers of Moog, Oberheim, ARP and Sequential Circuits, to name but a few.
Some time ago Doepfer used to give this book (or the German version) away for free if you purchased a full Doepfer system.
Getting it is better than buying it; for such a small book the price ( 36 USD ) is a bit too high IMHO...
Wizoo has quite an extensive collection of other English and German audio/ recording -books too.
You can find the other English books here
Publication Date: 1999 by Wizoo Publishing GmbH
More info on this book HERE