There exists more than one type of Mandarin tone sandhi.
The most basic is the Tone 3 possibly changing to Tone 2 under certain conditions.
Also, there is the half tone phenomenon.
Is there some place that assembles descriptions of all these things?
I know of some of the work of Duanmu San, Zhiming Bao, Moira Yip, and Yuenren Chao. Are there other bodies of related work?