Nebel, B. J., & Wright, R. T. (1993). Environmental science: The way the world works (4th.ed.). Prentice Hall.

Nebel, Bernard J., and Richard T. Wright. Environmental Science: The Way the World Works. 4th.ed. Englewood Cliffs: Prentice Hall, 1993.

Nebel, Bernard J., and Richard T. Wright. Environmental Science: The Way the World Works. 4th.ed. Prentice Hall, 1993.