Hi Kishore ,
These are the 3 best books for SAP CRM by SAP-Press .
These Books covers both functional and technical stuffs.
CRM is so closly spaced you can not segregate Functional and technical things as far as Web ui is considered.
1.Customizing and development .
http://www.sap-press.com/products/SAP-CRM-Web-Client-Customizing-and-Development.html
2. Technical principles and programming.
http://www.sap-press.com/products/SAP-CRM%3A-Technical-Principles-and-Programming.html
3. Comprehensive guide for developers .
http://www.sap-press.com/products/SAP-Web-Client%3A-A-Comprehensive-Guide-for-Developers.html
More ocer you can follow http://scn.sap.com/community/crm/webclient-ui-framework space .
Regards .