Title link takes you to a page containing dowloads of Sam Ecoff's electronic music books.

Fundamentals of Music Technology - On Synthesis
"I wrote a book a couple of years ago on modular synthesis to use in the courses I teach at a conservatory. It assumes zero knowledge of synthesis and it includes an example CD*. You may download a PDF of the book, below. One of the major shortcomings of my book (as I see it) is that it is specific to the ARP 2600, which is what I generally use to teach modular synthesis. It might be an interesting read for ARP fans, though. That having been said, it was my first attempt at writing a book, and there are some things that I would definitely do differently if I had it to do again."
Still sounds good to me.