A photo reference should of course contain plenty of photos, but here there may be too many, or maybe it's that they're crammed four or five to a page. I've worked with small print photos of my own as a reference and it's no bother ( I can enlarge them if I need to), but when a smallish image is one of a group on that same page, well...it's just too crowded.
Perhaps less would be more.
Maybe it's my merely-intermediate stature, but I'd rather a larger format, such as a volume called "America" (or "American Landscapes") that I found at the library, with one or two great photos to a page.
"Artist's Photo Reference: Landscapes" is helpfully organized into categories and sections within those categories, and offers a few demos. That's a good thing.
I may not unload this book, but I'll more likely hit the library for some general photography books.