Παραπομπή APA
(1981). How to sharpen your mental powers in business. New York: Alexander Hamilton Institute.
Παραπομπή Chicago StyleHow to Sharpen Your Mental Powers in Business. New York: Alexander Hamilton Institute, 1981.
Παραπομπή MLAHow to Sharpen Your Mental Powers in Business. New York: Alexander Hamilton Institute, 1981.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.