Avi Silberschatz's "Database System Concepts: Concurrency Control"
Read these slides, which cover two-phase locking timestamps, deadlocks, and multiversion concurrency control. As you read, focus on the mechanism and locks that affect concurrency control.
Click http://web.archive.org/web/20151123142935/http://www.cse.iitb.ac.in/~sudarsha/db-book/slide-dir/ch16.pdf link to open resource.