Rigorous scientific survey from 1988 of how agaves and cacti respond to changes in their environment. Lots of well-made charts and graphs summarize the fairly dry text. The book is interesting from two standpoints: (1) the ecology of how these plants exist in nature; and (2) ways these plants can be tweaked in a garden.
Surveys some older literature about agaves and cacti. In-depth chapter-by-chapter discussion of how these plants behave with respect to gas exchange & metabolism, water, temperature, light, nutrients, and productivity. All terms are defined when they first appear. You don't have to read all the way through if you're just curious about one thing.
Here are some species which appear frequently in the book. There are many others as well.
Carnegia gigantea (saguaro)
Opuntias (various, incl. ficus-indica and bigelovii)