RT Journal Article SR Electronic T1 A mean-variance approach to fundamental valuations JF The Journal of Portfolio Management FD Institutional Investor Journals SP 26 OP 32 DO 10.3905/jpm.1984.408978 VO 11 IS 1 A1 James Tobin YR 1984 UL https://pm-research.com/content/11/1/26.abstract AB