References:

1) http://www.cduniverse.com/
2) http://audio.tutsplus.com/articles/west-coast-east-coast-hip-hop-explained/
3) http://www.experiencefestival.com/hip_hop_rivalries_-_east_coast_vs_west_coast
4) http://www.hiphopgalaxy.com/East-Coast-hip-hop-hip-hop-2087.html
5) http://knowledgerush.com/kr/encyclopedia/West_Coast_hip_hop/