Hill, N. (1977). Success through positive mental attitude. Pocket book.
Cita Chicago (17th ed.)Hill, Napoleon. Success Through Positive Mental Attitude. New York: Pocket book, 1977.
Cita MLA (9th ed.)Hill, Napoleon. Success Through Positive Mental Attitude. Pocket book, 1977.
Atenció: Aquestes cites poden no estar 100% correctes.