RT Journal Article SR Electronic T1 Enhancing mean-variance analysis with options JF The Journal of Portfolio Management FD Institutional Investor Journals SP 67 OP 71 DO 10.3905/jpm.1985.409003 VO 11 IS 3 A1 Peter H. Ritchken YR 1985 UL https://pm-research.com/content/11/3/67.abstract AB