Cita APA (7th ed.)

Lucas, J., & McKennell, V. (1974). The Penguin book of playgroups. Penguin Books.

Cita Chicago (17th ed.)

Lucas, Joyce, i Vivienne McKennell. The Penguin Book of Playgroups. Harmondsworth ; Baltimore: Penguin Books, 1974.

Cita MLA (8th ed.)

Lucas, Joyce, i Vivienne McKennell. The Penguin Book of Playgroups. Penguin Books, 1974.