Sharp, A. M., Leftwich, R. H., & Register, C. A. (1992). Economics of social issues (10th. ed.). Irwin.

Sharp, Ansel M., Richard H. Leftwich, and Charles A. Register. Economics of Social Issues. 10th. ed. Boston: Irwin, 1992.

Sharp, Ansel M., et al. Economics of Social Issues. 10th. ed. Irwin, 1992.