APA (7th ed.) Citation

Valentine, C. W. (1950). The difficult child and the problem of discipline (5th ed.). Methuen.

Chicago Style (17th ed.) Citation

Valentine, C. W. The Difficult Child and the Problem of Discipline. 5th ed. Lond.: Methuen, 1950.

MLA (8th ed.) Citation

Valentine, C. W. The Difficult Child and the Problem of Discipline. 5th ed. Methuen, 1950.