Smith, G. A. 1., & Pun, A. (2006). How does Earth work?: Physical geology and the process of science. Upper Saddle River, N.J.: Pearson Prentice Hall.

Smith, Gary A. 1958-., and Aurora Pun. How Does Earth Work?: Physical Geology and the Process of Science. Upper Saddle River, N.J.: Pearson Prentice Hall, 2006.

Smith, Gary A. 1958-., and Aurora Pun. How Does Earth Work?: Physical Geology and the Process of Science. Upper Saddle River, N.J.: Pearson Prentice Hall, 2006.