APA

Christensen L. R., Cummings D. & Jorgenson D. W.Relative productivity levels, 1947-1973. : .

Chicago

Christensen Laurits R, Cummings D and Jorgenson Dale W.Relative productivity levels, 1947-1973. : .

Harvard

Christensen L. R., Cummings D. and Jorgenson D. W.Relative productivity levels, 1947-1973. : .

MLA

Christensen Laurits R, Cummings D and Jorgenson Dale W.: . .