The Book
The required text for the class is available as a pdf.
Principles of Programming Languages is Copyright © 2002-2018 Scott F. Smith and is released under the Creative Commons Attribution-Share Alike 3.0 United States License. To view a copy of the license, visit this link.
The Fb Development Kit (FbDK)
The FbDK is a framework for writing the interpreters discussed in the book. The binaries are fully working versions of the interpreters, and the source is simply the framework with a dummy implementation of the interpreters.