(1955). Keys to happiness: A Reader's Digest guide to successful living. The Reader's Digest Association.
Cita Chicago (17th ed.)Keys to Happiness: A Reader's Digest Guide to Successful Living. The Reader's Digest Association, 1955.
Cita MLA (9th ed.)Keys to Happiness: A Reader's Digest Guide to Successful Living. The Reader's Digest Association, 1955.
Atenció: Aquestes cites poden no estar 100% correctes.