Pritchett, P. (2007). Hard optimism: How to succeed in a world where positive wins. New York: McGraw-Hill.
Παραπομπή Chicago StylePritchett, Price. Hard Optimism: How to Succeed in a World Where Positive Wins. New York: McGraw-Hill, 2007.
Παραπομπή MLAPritchett, Price. Hard Optimism: How to Succeed in a World Where Positive Wins. New York: McGraw-Hill, 2007.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.