Other correlation resources:
Fundamental Relationship Between An Index's Volatility And The Correlation And Average Volatility Of Its Components, by Sebastien Bossu, Yi Gu
Dispersion Trading in German Option Market, by Jonas Lisauskas
Studying the Properties of the Correlation Trades, by Cayetano Gea Carrasco
Analysis and Development Of Correlation Arbitrage Strategies on Equities, Yujin Chloe Choi
and best for the last Dispersion Trading Reading List, from condoroptions.com