RIGGS JAMES L. (1983). PRODUCTIVITY BY OBJECTIVES. PRENTICE -HALL INTERNATIONAL, INC.
Lua i Stíl Chicago (17ú heag.)RIGGS JAMES L. PRODUCTIVITY BY OBJECTIVES. NEW JERSE: PRENTICE -HALL INTERNATIONAL, INC, 1983.
Lua MLA (9ú heag.)RIGGS JAMES L. PRODUCTIVITY BY OBJECTIVES. PRENTICE -HALL INTERNATIONAL, INC, 1983.
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