APA (7th ed.) Citation

Skemp, R. R. (1971). The psychology of learning mathematics. Penguin Books.

Chicago Style (17th ed.) Citation

Skemp, Richard R. The Psychology of Learning Mathematics. Middlesex, Eng: Penguin Books, 1971.

MLA (9th ed.) Citation

Skemp, Richard R. The Psychology of Learning Mathematics. Penguin Books, 1971.