Just as clarification, CUP gave me complementary copies of these two books in return for my views on the market for amateur astronomy books in general and on spectroscopy in particular which they asked me about this some time ago.
I have long been a fan of Richard Walker’s Atlas in its free on line format for many years and I was pleased to find that CUP did a good job transferring it to print.
I do have some reservations about the accompanying “Spectroscopy for Amateur Astronomers” though which is based on two other on line documents previously published by Richard. It is a useful reference book with a good list of references for further reading but the practical parts are somewhat limited to what Richard has worked on in preparation of his atlas and may have benefited from wider input from other experienced amateurs . For example the use of flats and difficulties of flux calibration he mentions are areas which, while tricky subjects, have largely been successfully tackled by other amateurs. I would have preferred these areas and other areas to have been addressed head on in more detail rather than just put in the “too difficult for amateurs” category.This is my personal view of course which I did convey to CUP when they originally asked for my comments on an early draft.
Robin