APA (7th ed.) Citation

De Villiers, P. A., & De Villiers, J. G. (1979). Early language / Peter A. de Villiers and Jill G. de Villiers. Open Books.

Chicago Style (17th ed.) Citation

De Villiers, Peter A., and Jill G. De Villiers. Early Language / Peter A. De Villiers and Jill G. De Villiers. London: Open Books, 1979.

MLA (9th ed.) Citation

De Villiers, Peter A., and Jill G. De Villiers. Early Language / Peter A. De Villiers and Jill G. De Villiers. Open Books, 1979.

Warning: These citations may not always be 100% accurate.