I happen to own a paper copy of this book, and as usual for sharpening books, they throw in a chapter on axes as an afterthought. Sharpening an ax is different enough from most other sharpening that you should get a specialized text for it. It's not that difficult or terribly specialized, but knife sharpeners always seem to want to apply the ideas of knife sharpening to axes, which isn't quite right all the time.
Two books I recommend for axes are "One Moving Part", the USFS ax manual, probably the best (only?) work that they ever did:
https://www.fs.usda.gov/t-d/pubs/pdfpubs/pdf18232812P/1823-2...
And "The Ax Book" by Dudley Cook, which you'll have to buy a paper copy of. (I don't suggest you round the corners of your axes as he suggests though)
The old USFS ax manual, "An Ax to Grind", even had a companion video which you can find on youtube, though if you're new to sharpening the instructions could be more clear IMO: