Ryan, T. A. (1947). Work and effort: The psychology of production. Ronald Press Co.
Lua i Stíl Chicago (17ú heag.)Ryan, Thomas A. Work and Effort: The Psychology of Production. New York: Ronald Press Co, 1947.
Lua MLA (8ú heag.)Ryan, Thomas A. Work and Effort: The Psychology of Production. Ronald Press Co, 1947.
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