https://chessprogramming.wikispaces.com/Flipping+Mirroring+and+Rotating
https://www.hackerrank.com/contests/gamathon/challenges/gomoku

Heuristics and Threat-Space-Search in Connect 5
http://isites.harvard.edu/fs/docs/icb.topic707165.files/pdfs/Kulev_Wu.pdf

https://chalmersgomoku.googlecode.com/files/allis1994.pdf