Saurabh
http://bitsavers.org/bits/Xerox/Ventura/doc/610E03760_Ventura_Publisher_1.1_Reference_1987.pdf
is the first technical manual that I read cover to cover.

It is an excellent guide on how to make a complex subject easy to understand and exciting - even to a 9 year old.

John Meyer was one of the three members of the team that coded the entire Ventura Publisher software. And he wrote the 500+ page manual single handledly.

Imagine. Creating the first successful desktop publishing software. Then using your own software to create a 500+ page manual that explains desktop publishing and your software to a global audience. People were really living it up in the '80s.