263 Points
Joined January 2010
For DT: Refer T.N. Manoharan book(snowhite publication). you will be able to compelete the book in 45 days.
For Costing: I prefered Dr.J.B. Gupta(Its good for self study). Start with OR first, it would take 10-15 days(assuming u are studing for 2.5-3 hours)
then start with Costing.