RT Journal Article SR Electronic T1 Is Beta a Useful Measure of Security Risk? JF The Journal of Portfolio Management FD Institutional Investor Journals SP 23 OP 31 DO 10.3905/jpm.1981.23 VO 7 IS 2 A1 Robert F. Vandell YR 1981 UL https://pm-research.com/content/7/2/23.abstract AB