Warner, W. L., Riper, P. P. v., Martin, N. H., & Collins, O. F. (1963). The american federal executive: A study of the social and personal characteristics of the civilian and military leaders of the United States Federal Government. Yale University Press.

Warner, W. Lloyd, Paul P. van Riper, Norman H. Martin, and Orvis F. Collins. The American Federal Executive: A Study of the Social and Personal Characteristics of the Civilian and Military Leaders of the United States Federal Government. New Haven: Yale University Press, 1963.

Warner, W. Lloyd, et al. The American Federal Executive: A Study of the Social and Personal Characteristics of the Civilian and Military Leaders of the United States Federal Government. Yale University Press, 1963.