Here are some books for beginners and for more advanced amateurs. You can download them.
The Observing Guide to the Messier Marathon - Don Machholz
http://www.scribd.com/doc/7074158/Th...n-Don-Machholz
Double and Multiple Stars and How to Observe Them - James Mullaney
http://www.scribd.com/doc/6874098/Do...James-Mullaney
Star Clusters And How To Observe Them - Mark Allison
http://www.scribd.com/doc/6874227/St...o-Observe-Them
Nebulae and How to Observe Them - Steven R. Coe
http://www.scribd.com/doc/6874175/Ne...m-Steven-R-Coe
The Herschel Objects And How To Observe Them - Jame Mullaney
http://www.scribd.com/doc/6874255/Th...-Jame-Mullaney
More at:
http://www.springer.com/astronomy/po...&resultStart=0