Some old books from the 1940's would be a good start. I actually had to work on a regnerative receiver that some idiiot used in a modern position locating system. I would highly recommend not using such a design. It is basically and oscillator that sits there churning out a sawtooth bias waveform, until an RF signal appears and it locks onto it. The benefit was that, as an oscillator, you got nearly infinite gain from one device. The drawback was, of course, that the oscillations were flakier than dandruff! With modern integrated circuits, where you can get plenty of gain from one chip, you would get much better performance by using superhetrodyne, ash receiver, etc.