PT - JOURNAL ARTICLE AU - Kenneth J Winston TI - The “Efficient Index” and Prediction of Portfolio Variance AID - 10.3905/jpm.1993.409446 DP - 1993 Apr 30 TA - The Journal of Portfolio Management PG - 27--34 VI - 19 IP - 3 4099 - https://pm-research.com/content/19/3/27.short 4100 - https://pm-research.com/content/19/3/27.full