Thoman, R. S., Conkling, E. C., & Yeates, M. (1968). The geography of economic activity. McGraw-Hill.

Thoman, Richard S., Edgar C. Conkling, and Maurice Yeates. The Geography of Economic Activity. New York: McGraw-Hill, 1968.

Thoman, Richard S., et al. The Geography of Economic Activity. McGraw-Hill, 1968.