I don't know of any books on gamification specifically, but would be interested if others do. The Deconstructor of Fun blog is a consistent resource on microtransactions. [0]

For an introduction to game design in the general sense, there is Jesse Schell's The Art of Game Design. [1] I think it's better to approach gamification as something that emerges from a holistic appreciation of game design; rather than gamification as a goal in-and-of-itself. But that's the long way. I don't know any shorter.

[0] https://www.deconstructoroffun.com/blog

[1] https://schellgames.com/art-of-game-design/