VALKENBURG, S. v. (1960). Elements of political geography.-- ed.2. Prentice-Hall.
芝加哥风格引文VALKENBURG, Samuel van. Elements of Political Geography.-- Ed.2. New Jersey: Prentice-Hall, 1960.
MLA引文VALKENBURG, Samuel van. Elements of Political Geography.-- Ed.2. Prentice-Hall, 1960.
警告：这些引文格式不一定是100％准确.