Thoman, R. S., Conkling, E. C., & Yeates, M. (1968). The geography of economic activity. McGraw-Hill.
Cita Chicago (17th ed.)Thoman, Richard S., Edgar C. Conkling, i Maurice Yeates. The Geography of Economic Activity. New York: McGraw-Hill, 1968.
Cita MLA (8th ed.)Thoman, Richard S., et al. The Geography of Economic Activity. McGraw-Hill, 1968.
Atenció: Aquestes cites poden no estar 100% correctes.