Different types of Blind Madmen
There are at least two Blind Madmen:
One is the type found in both Black and White clan maps (Shi Zhang and Zhengzhou, respectively)
The other type is the level 46 Monstrous Blind Madman and found only in Shi Zhang on the Plain of White Sand (around coordinates 785, 320).
The Monstrous Blind Madman drops the Dian Cang's book.