Every day in my work I refer Books Online. It is the online documentation on Microsoft SQL Server, which is updated periodically. One of the good things about SQL Server Books Online is that it can downloaded and installed locally on a client machine so as not to go online every time you need to refer the official SQL Server documentation.
Follow this link to download SQL Server 2008 Books Online >> Microsoft SQL Server 2008 Books Online (October 2009)
— Bru Medishetty