Programming C# - Programming C# teaches this new language in a way that experienced programmers will appreciate--by grounding its application firmly in the context of Microsoft's .NET platform and the development of desktop and Internet applications. - http://www.oreilly.com/catalog/progcsharp/
C# Essentials - Quick introduction to C# (C-sharp) language and .NET Framework, plus a C# language reference, and the details experienced programmers need to evaluate or begin implementing this new language. - http://www.oreilly.com/catalog/csharpess/