作者:GOLLOP, FM; ROBERTS, MJ
作者单位:Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park
作者:FROYEN, RT; WAUD, RN
作者单位:University of North Carolina; University of North Carolina Chapel Hill; National Bureau of Economic Research
作者:OHSFELDT, RL; SMITH, BA
作者单位:University of Houston System; University of Houston