RT Journal Article SR Electronic T1 Portfolio Theory is Still Alive and Well JF The Journal of Investing FD Institutional Investor Journals SP 45 OP 46 DO 10.3905/joi.3.3.45 VO 3 IS 3 A1 Paul D. Kaplan A1 Laurence B. Siegel YR 1994 UL https://pm-research.com/content/3/3/45.abstract AB