Freivalds, A., & Niebel, B. W. (2009). Niebel's methods, standards, and work design (12th ed., international ed.). McGraw-Hill Higher Education.
Lua i Stíl Chicago (17ú heag.)Freivalds, Andres, agus Benjamin W. Niebel. Niebel's Methods, Standards, and Work Design. 12th ed., international ed. Boston: McGraw-Hill Higher Education, 2009.
Lua MLA (9ú heag.)Freivalds, Andres, agus Benjamin W. Niebel. Niebel's Methods, Standards, and Work Design. 12th ed., international ed. McGraw-Hill Higher Education, 2009.
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