Levinson, N. (1940). Gap and density theorems. American Mathematical Society.
芝加哥风格引文Levinson, Norman. Gap and Density Theorems. New York: American Mathematical Society, 1940.
MLA引文Levinson, Norman. Gap and Density Theorems. American Mathematical Society, 1940.
警告：这些引文格式不一定是100％准确.