KZ指数(1.Lamont et al,2011 "financial constraints and stock returns "
2. KAPLAN AND ZINGALES,1997 "DO INVESTMENT-CASH FLOW SENSITIVITIES PROVIDE
USEFUL MEASURES OF FINANCING CONSTRAINTS")
ww指数(whited and wu,2006 “Financial Constraints Risk”)
SA指数(Hadlock and Pierce,2010 “New Evidence on Measuring Financial Constraints: Moving Beyond the KZ Index”)