Hi Ahmed
A new book just came out
Implementing Cisco UCS Solutions
http://www.packtpub.com/implementing-cisco-ucs-solutions/book?utm_source=mention.com&utm_medium=Links&utm_campaign=sales%20db
The classical one (no more up to date) is
Cisco Unified Computing System (UCS) (Data Center): A Complete Reference Guide to the Cisco Data Center Virtualization Server Architecture (Networking Technology)
1st (first) Edition by Gai, Silvano, Salli, Tommi, Andersson, Roger published by Cisco
Cisco Live has also many UCS introduction session, e.g.
https://www.ciscolive.com/online/connect/sessionDetail.ww?SESSION_ID=6287
BRKCOM-8636 - Introduction to Cisco Unified Computing System (Cisco UCS) Central - 90 Mins
This includes VoD and pdf