The document in Kernel:
https://www.kernel.org/doc/Documentation/cpu-freq/governors.txt
Brief compares:
http://wiki.rootzwiki.com/CPU_Governors
http://forum.xda-developers.com/showthread.php?t=1736168
Interactive Governor: https://lkml.org/lkml/2012/2/7/483
Related Paper:
http://dl.acm.org/ft_gateway.cfm?id=2448665&ftid=1352015&dwn=1&CFID=357950533&CFTOKEN=77085944