(1955). Keys to happiness: A Reader's Digest guide to successful living. The Reader's Digest Association.
Cita Chicago Style (17a ed.)Keys to Happiness: A Reader's Digest Guide to Successful Living. The Reader's Digest Association, 1955.
Cita MLA (9a ed.)Keys to Happiness: A Reader's Digest Guide to Successful Living. The Reader's Digest Association, 1955.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.