PT - JOURNAL ARTICLE AU - James C. Ryan AU - Mark Kritzman TI - Reply AID - 10.3905/jpm.1980.408777 DP - 1980 Oct 31 TA - The Journal of Portfolio Management PG - 82 VI - 7 IP - 1 4099 - https://pm-research.com/content/7/1/82.short 4100 - https://pm-research.com/content/7/1/82.full