hi i am amit from surat .if you want to pass the gate 2013 , use this books namely machine design by amitabh ghosh. theory of machine by s.s rattan, manufacturing technology by r .k. jain mathematics by Dr. b.s. agrwal
Iam giving you some tips related to GATE.
1>Ur basic knowledge should be clear
2>You must check the syllabus,previous year question paper.
3>Start preparing notes& visit group discurssion forum.that will help you a lot
For study material you can check this website