Programming Microsoft LINQ
This book covers Language Integrated Query (LINQ) deeply and widely. The main goal is to give you a complete understanding of what LINQ is, as well as what to do and what not to do with LINQ. The target audience for this book is .NET developers with a good knowledge of Microsoft .NET 2.0 who are wondering whether to upgrade their expertise to Microsoft .NET 3.5.
You can download and read sample chapters from the follwing link
Link: http://programminglinq.com/
Reference: http://www.microsoft.com/learning/en/us/book.aspx?ID=10827