Textbook in PDF format

What is Squeak?
Squeak is a modern, open-source, fully-featured implementation of the Smalltalk programming language and environment.
Squeak is highly portable — even its virtual machine is written almost intirely in Smalltalk, making it easy to debug, analyze, and change. Squeak is the vehicle for a wide range of innovative projects from multimedia applications and educational platforms to commercial web development environments