The Fun of Motivation : Crossing the Threshold Concepts, by Mary Francis
Games in Libraries : Essays on Using Play to Connect and Instruct, edited by Breanne A. Kirsch
The Gamification of Learning and Instruction : Game-based Methods and Strategies for Training and Education, by Karl M. Kapp
The Gamification of Learning and Instruction Fieldbook : Ideas Into Practice, by Karl M. Kapp, Lucas Blair, Rich Mesch
Advanced Game Design with HTML5 and JavaScript, by Rex van der Spuy
Gamification : a Practical Guide for Librarians by Elizabeth McMunn-Tetangco
Gamification for Human Factors Integration : Social, Education, and Psychological Issues, edited by Jonathan Bishop
Gamification in Education : Breakthroughs in Research and Practice by Information Resources Management Association, editor
Gamification in Learning and Education : Enjoy Learning Like Gaming by Sangkyun Kim, Kibong Song, Barbara Lockee, John Burton
The Gamification of Learning and Enstruction : Game-based Methods and Strategies for Training and Education by Karl Kapp
Gamification : Using Game Elements in Serious Contexts, edited by Stefan Stieglitz, et al.
The Multiplayer Classroom: Designing Coursework As a Game by Lee Sheldon
Serious Game Design and Development : Technologies for Training and Learning, edited by Jan Cannon-Bowers, Clint Bowers
Wikipedia article on Gamification
Try searching in ERIC, the Education Resources Information Center from the Federal Department of Education