Christensen. (1980). Relative productivity levels, 1947- 1973: An international comparison. Cambrridge: Harvard Institute for Economic Research.
Čikaški stil citiranjaChristensen. Relative Productivity Levels, 1947- 1973: An International Comparison. Cambrridge: Harvard Institute for Economic Research, 1980.
MLA način citiranjaChristensen. Relative Productivity Levels, 1947- 1973: An International Comparison. Cambrridge: Harvard Institute for Economic Research, 1980.
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