RT Journal Article SR Electronic T1 Efficient portfolios vs. index funds JF The Journal of Portfolio Management FD Institutional Investor Journals SP 72 OP 74 DO 10.3905/jpm.1978.408661 VO 5 IS 1 A1 Richard Williams A1 Peter W. Bacon YR 1978 UL https://pm-research.com/content/5/1/72.abstract AB