RT Journal Article SR Electronic T1 Understanding Aggregate Default Rates of High-Yield Bonds JF The Journal of Fixed Income FD Institutional Investor Journals SP 55 OP 61 DO 10.3905/jfi.1997.408202 VO 7 IS 1 A1 Jean Helwege A1 Paul Kleiman YR 1997 UL https://pm-research.com/content/7/1/55.abstract AB