The Labor of Older Americans: Retirement of Men On and Off the Job, 1870–1937
估算了1870-1937年美国60岁以上男性的劳动参与率，发现退休频率高于以往认知，且许多老年工业工人转向低薪低强度工作，这种“在职退休”使退休过渡更平缓。
Labor force participation rates for American men sixty and over are estimated for the period 1870 through 1937. They suggest a higher frequency of retirement and quite different trends in the incidence of retirement than have usually been supposed. Evidence is also presented to establish that many older industrial workers changed to less renumerative and less demanding occupations late in their working life. This “on-the-job retirement” may have made the transition from employment to full retirement less sudden than today.