Ullrich, R. A. (1981). Motivation methods that work. Prentice-Hall.
芝加哥风格引文Ullrich, Robert A. Motivation Methods That Work. Englewood Cliffs, N.J.: Prentice-Hall, 1981.
MLA引文Ullrich, Robert A. Motivation Methods That Work. Prentice-Hall, 1981.
警告：这些引文格式不一定是100％准确.