RT Journal Article SR Electronic T1 Put—call ratios and market timing effectiveness JF The Journal of Portfolio Management FD Institutional Investor Journals SP 25 OP 28 DO 10.3905/jpm.1988.409184 VO 15 IS 1 A1 Randall S. Billingsley A1 Don M. Chance YR 1988 UL https://pm-research.com/content/15/1/25.abstract AB