Hi Abdul,
What Ankit expressed is exactly my experience too. Not only in ABAP, in any field the speed and effectiveness of learning is many times more, when we learn by working on real time tasks. Such learnings will not easily erode.
Also, as he said, SCN is a great place for this kind of learning.
But, I appreciate your interest to go through books, which have certainly their own significance, like following the rules of the space (ABAP programming).and advanced concepts etc. Also this will certainly bring you an edge over others in knowledge, thus being the only tool to fulfill your desire to be the best in the space. But your foundation should be the first one.
Browse through this link for good books on SAP. (This page gives you ABAP books).
http://www.sap-press.com/search.php?search_query=abap&x=0&y=0
Jogeswara Rao K
