Williams, E. T., & Nicolls, C. S. (1981). The Dictionary of National Biography: Twenthieth Century: Ed. by E[dgar] Trevor] Williams and C[hristine] S[tephanie] Nicholls. Oxford Univ. Press.

Williams, Edgar Trevor, and Christine Stephanie Nicolls. The Dictionary of National Biography: Twenthieth Century: Ed. by E[dgar] Trevor] Williams and C[hristine] S[tephanie] Nicholls. Oxford: Oxford Univ. Press, 1981.

Williams, Edgar Trevor, and Christine Stephanie Nicolls. The Dictionary of National Biography: Twenthieth Century: Ed. by E[dgar] Trevor] Williams and C[hristine] S[tephanie] Nicholls. Oxford Univ. Press, 1981.