GiST and Gin technical doc - Mailing list pgsql-general

Hi there,

I'm having trouble finding technical documentation about GiST, Gin and
TSearch2.

I am particularly interested in the internal data structure of a GiST-ed
or Gin-ed index, and the availability of searches by proximity.

Does anyone know of a good place to find such doc, outside from the
source code (I'm not too much into C/C++)?

Thank you,

Yannick