Sfm reference books for conceptual understanding ??

Hi friends, i've recently purchased G.sekar Padhuka book for SFM, but i am not at all satisfied with Conceptual topics, it is just loaded with Practical problems......

Heard about books like -An.Sridhar,pattabhiram & J.B gupta for conecptual in-depth study........please suggest which one is better or can i go with any of these three ??