C# School Book
- Free 330-page ebook giving a full introduction to programming in C#, from the very basics to GUI and database development.
- http://www.programmersheaven.com/2/csharpbook

C# Book Online
- A book that covers all the major aspects of the programming language.
- http://www.codereference.com/book/csharp.aspx

Microsoft C# Language Specifications
- Includes book review and links for purchasing.
- http://www.microsoft.com/mspress/books/5490.aspx

Inside C#
- By Tom Archer, advertises itself as a detailed look at the internal architecture of C#.
- http://www.microsoft.com/mspress/books/5027.aspx

C# Precisely
- A concise book describing the C# programming language, version 2.0, including generics, iterators, anonymous methods, nullable value types and partial type declarations. All example programs from the book. Links.
- http://www.dina.kvl.dk/~sestoft/csharpprecisely/

Professional C#
- Now on its second edition, the book was updated to run on the Final Release of .Net. The book covers C# language syntax, Web Services, Windows Development, ASP, Data Access, .Net Remoting and some concepts of object-oriented programming.
- http://www.wrox.com/books/0764543989.shtml