Proctor, W. M. (1933). Vocations: The world's work and its workers (Rev. and enl. ed.). Houghton Mifflin Company.
Lua i Stíl Chicago (17ú heag.)Proctor, William Martin. Vocations: The World's Work and Its Workers. Rev. and enl. ed. Boston : New York [etc.]: Houghton Mifflin Company, 1933.
Lua MLA (8ú heag.)Proctor, William Martin. Vocations: The World's Work and Its Workers. Rev. and enl. ed. Houghton Mifflin Company, 1933.
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