What are not gate flip flop and which book should I refer tooooo

There are all sorts of books available on the subject - here's an Internet source:

NOR Gate Flip-Flop Tutorial - Flip Flop Tutorials and Circuits - Electronics Hobby Projects (http://www.hobbyprojects.com/flip_flop/NOR_gate_flip-flop.html)

Thanks sir , i will definitely refer to the link

Sry sir,
I checked the linkbut it was not helpful .it was only an experiment based on flip-flop.anyways thanks you sir.