APA   Click to copy
Colwell, R. K., & Hurtt, G. C. (1994). Nonbiological gradients in species richness and a spurious Rapoport effect. The American Naturalist, 144, 570–595.

Chicago/Turabian   Click to copy
Colwell, Robert K, and George C Hurtt. “Nonbiological Gradients in Species Richness and a Spurious Rapoport Effect.” The American Naturalist 144 (1994): 570–595.

MLA   Click to copy
Colwell, Robert K., and George C. Hurtt. “Nonbiological Gradients in Species Richness and a Spurious Rapoport Effect.” The American Naturalist, vol. 144, University of Chicago Press, 1994, pp. 570–95.

@article{colwell1994a,
  title = {Nonbiological gradients in species richness and a spurious Rapoport effect},
  year = {1994},
  journal = {The American Naturalist},
  pages = {570--595},
  publisher = {University of Chicago Press},
  volume = {144},
  author = {Colwell, Robert K and Hurtt, George C}
}