http://qrp.ru/files/literature/category/15-cqqrp?download=43%3Acq-qrp-30
He touches on some lesser-explored topics like broadband (untuned) regeneration, multi-stage regeneration, regenerative antennas and their effect on the surrounding electromagnetic field, etc. The article starts on page 4. If your Russian language skills are not up to par, here's Google's translation (unfortunately without images): http://bit.ly/1v3lDk1