APA استشهاد

Gregory, P. R. S. C. (1980). Comparative economic systems (5th.Ed.). Houghton Mifflin.

استشهاد بنمط شيكاغو

Gregory, Paul R. Stuart,robert C. Comparative Economic Systems. 5th.Ed. Boston: Houghton Mifflin, 1980.

MLA استشهاد

Gregory, Paul R. Stuart,robert C. Comparative Economic Systems. 5th.Ed. Houghton Mifflin, 1980.