Torben Ægidius Mogensen's "Basics of Compiler Design, Chapter 6: Type Checking"
Read Chapter 6, which presents an overview of type checking, nicely organized: symbol table environment, type checking for expressions, functions, and then, for programs.
Click http://web.archive.org/web/20120915222417/http://www.diku.dk/hjemmesider/ansatte/torbenm/Basics/basics_lulu2.pdf link to open resource.