GAO Red Book: Principles of Federal Appropriations Law
A gem tucked away in the arcane literature of budgeters. The GAO publishes the bible on federal appropriations law. To those not involved in this subject, one would think it is filled with hard to understand concepts. To the contrary, it is written in a non-legal and non-technical terms with a very subtle sense of humor. In addition it presents an in-depth history of the federal appropriations process.