RT Journal Article SR Electronic T1 The cyclical pattern in corporate bond quality JF The Journal of Portfolio Management FD Institutional Investor Journals SP 26 OP 29 DO 10.3905/jpm.1980.408736 VO 6 IS 2 A1 Michael G. Ferri A1 Charles G. Martin YR 1980 UL https://pm-research.com/content/6/2/26.abstract AB