Time management is very much important in IIT JAM. The eduncle test series for IIT JAM Mathematical Statistics helped me a lot in this portion. I am very thankful to the test series I bought from eduncle.
Nilanjan Bhowmick AIR 3, CSIR NET (Earth Science)
Ruby negi
arfken is the best book ,it's language , question everything is good.. Erwin Kreyzig is good book but I don't like so I suggest you to go through arfken which is strongly recommended in IIT's, Universities... best regards...