For Part 29 Rotary work the FAA guide book AC29-2C (I think this is the latest edition) is available on the FAA website. Sister publication available for Part 27 (and no doubt aeroplanes small and large too.) Look on the EASA site as well.
I know CAA Flight Dept have used 29-2C quite a bit as reference.
Endorse the Alastair Cooke/ Eric Fitzpatrick book too.