APA (7th ed.) Citation

Ware, C. F., Panikkar, K. M., & Romein, J. M. (1966). The twentieth century. Unwin Brothers.

Chicago Style (17th ed.) Citation

Ware, Caroline F., K. M. Panikkar, and J. M. Romein. The Twentieth Century. London: Unwin Brothers, 1966.

MLA (9th ed.) Citation

Ware, Caroline F., et al. The Twentieth Century. Unwin Brothers, 1966.