Ladd, D. R. (1957). Cost data for the management of railroad passenger service. Division of Research Graduate School of Business Administration Harvard University.
Chicago-referens (17:e uppl.)Ladd, Dwight R. Cost Data for the Management of Railroad Passenger Service. Boston: Division of Research Graduate School of Business Administration Harvard University, 1957.
MLA-referens (9:e uppl.)Ladd, Dwight R. Cost Data for the Management of Railroad Passenger Service. Division of Research Graduate School of Business Administration Harvard University, 1957.
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