Yorkey, R. (1981). Reply requested: 30 letters of advice. Addison Wesley Publishing Company.
Citazione stile Chigago Style (17a edizione)Yorkey, Richard. Reply Requested: 30 Letters of Advice. Reading: Addison Wesley Publishing Company, 1981.
Citatione MLA (9a ed.)Yorkey, Richard. Reply Requested: 30 Letters of Advice. Addison Wesley Publishing Company, 1981.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.