APA (7th ed.) Citation

Horn, S. (1991). Concentration!: How to focus for success. Crisp Publications.

Chicago Style (17th ed.) Citation

Horn, Sam. Concentration!: How to Focus for Success. Los Altos, Calif: Crisp Publications, 1991.

MLA (9th ed.) Citation

Horn, Sam. Concentration!: How to Focus for Success. Crisp Publications, 1991.