Popkin, G. S. (1989). Comprehensive structured COBOL (3rd ed.). PWS-Kent Pub. Co..
芝加哥风格引文Popkin, Gary S. Comprehensive Structured COBOL. 3rd ed. Boston: PWS-Kent Pub. Co., 1989.
MLA引文Popkin, Gary S. Comprehensive Structured COBOL. 3rd ed. PWS-Kent Pub. Co., 1989.
警告：这些引文格式不一定是100％准确.