RT Journal Article SR Electronic T1 The judgment of economic science on rational portfolio management JF The Journal of Portfolio Management FD Institutional Investor Journals SP 4 OP 12 DO 10.3905/jpm.1989.409238 VO 16 IS 1 A1 Paul A. Samuelson YR 1989 UL https://pm-research.com/content/16/1/4.abstract AB