Hillis, N. D. (1913). The quest of happiness: A study of victory over life's troubles. The Macmillan company; Macmillan & co., ltd..
Chicago-referens (17:e uppl.)Hillis, Newell Dwight. The Quest of Happiness: A Study of Victory over Life's Troubles. New York, London: The Macmillan company; Macmillan & co., ltd., 1913.
MLA-referens (8:e uppl.)Hillis, Newell Dwight. The Quest of Happiness: A Study of Victory over Life's Troubles. The Macmillan company; Macmillan & co., ltd., 1913.
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