The book C# Precisely, second edition (MIT Press, February 2012) gives a concise description of the C# programming language up to version 4.0, plus the facilities for asynchronous programming that will be appear with C# 4.5 or 5.0.
The book has 246 pages, a comprehensive index, and 256 examples. The complete ready-to-run examples are available for download below.
Here's bonus note that summarizes the results of C# floating-point operations; they are mostly as expected for the IEEE 754 standard. (January 2009).
One more bonus note about microbenchmarks with C# source code (August 2013).
There is a list of errata.
Order it from Amazon.com or Amazon.co.uk.
The first edition of C# Precisely gave a concise description of the C# programming language, version 2.0, including generics, iterators, anonymous methods, nullable value types, and partial type declarations, but excluding most of Microsoft's .Net Framework class libraries except threads, input-output, and generic collection classes.
The book has 204 pages, a comprehensive index, and 209 examples.
The second printing from 2006 contains all necessary updates for the released version of C# 2.0 (Visual Studio 2005).
Bibliographic data, old version: P. Sestoft and Henrik I. Hansen, C# Precisely, The MIT Press 2004; second updated printing 2006. ISBN 0-262-69317-8. List price: US $21.95. The book's page at MIT Press. Published also by Prentice-Hall India 2005.