1. Callicott, J.B. 1986. "On the Intrinsic Value of Nonhuman Species." The Preservation of Species: The Value of Biological Diversity (pp. 156-162), B.G. Norton, ed. Princeton, NJ: Princeton University Press.
2. Callicott, J.B. 1989. "Animal Liberation-A Triangular Affair." In Defense of the Land Ethic (pp. 15-38), J.B. Callicott, ed. New York: State University of New York Press.
3. The uses of Martian ice
4. Population density and body size in mammals