Books from www.amazon.co.uk
If you are serious about sql server or even just interested then this is a book you cannot do without.
I would advise reading it from cover to cover - it is well written and informative. Then keep it for reference.
Joe Celko has been involved with sql development for a long time and is always a good read.
This is not specific to sql server but gives a lot of information about using sql.
The book about trees gives useful insights for anyone dealing with linked data
OK I haven't read this but it is well regarded as are all the Guru series.