APA (7th ed.) Citation

De Villiers, P. A., & De Villiers, J. G. (1979). Early language. Harvard University Press.

Chicago Style (17th ed.) Citation

De Villiers, Peter A., and Jill G. De Villiers. Early Language. Cambridge, Mass.: Harvard University Press, 1979.

MLA (8th ed.) Citation

De Villiers, Peter A., and Jill G. De Villiers. Early Language. Harvard University Press, 1979.