APA (7th ed.) Citation

De Bono. (1999). Six thinking hats (Revised and updated ed.). Little Brown and Company.

Chicago Style (17th ed.) Citation

De Bono. Six Thinking Hats. Revised and updated ed. New York: Little Brown and Company, 1999.

MLA (8th ed.) Citation

De Bono. Six Thinking Hats. Revised and updated ed. Little Brown and Company, 1999.