Williamson, H. F., & Smalley, O. A. (1957). Northwestern Mutual Life: A century of trusteeship. Northwestern University Press.
芝加哥风格引文Williamson, Harold Francis, 与 Orange A. Smalley. Northwestern Mutual Life: A Century of Trusteeship. Evanston, Ill: Northwestern University Press, 1957.
MLA引文Williamson, Harold Francis, 与 Orange A. Smalley. Northwestern Mutual Life: A Century of Trusteeship. Northwestern University Press, 1957.
警告：这些引文格式不一定是100％准确.