Freeman, H. (1962). Finite differences for acturial students (2nd.). Univ. Press.
芝加哥风格引文Freeman, Harry. Finite Differences for Acturial Students. 2nd. Cambridge: Univ. Press, 1962.
MLA引文Freeman, Harry. Finite Differences for Acturial Students. 2nd. Univ. Press, 1962.
警告：这些引文格式不一定是100％准确.