Lucas, J., & McKennell, V. (1974). The Penguin book of playgroups. Penguin Books.
芝加哥风格引文Lucas, Joyce, 与 Vivienne McKennell. The Penguin Book of Playgroups. Harmondsworth ; Baltimore: Penguin Books, 1974.
MLA引文Lucas, Joyce, 与 Vivienne McKennell. The Penguin Book of Playgroups. Penguin Books, 1974.
警告：这些引文格式不一定是100％准确.