APA   Click to copy
Barber, N. A., & Marquis, R. J. (2009). Spatial variation in top-down direct and indirect effects on white oak (Quercus alba L.). The American Midland Naturalist, 162, 169–179.

Chicago/Turabian   Click to copy
Barber, Nicholas A, and Robert J Marquis. “Spatial Variation in Top-down Direct and Indirect Effects on White Oak (Quercus Alba L.).” The American Midland Naturalist 162 (2009): 169–179.

MLA   Click to copy
Barber, Nicholas A., and Robert J. Marquis. “Spatial Variation in Top-down Direct and Indirect Effects on White Oak (Quercus Alba L.).” The American Midland Naturalist, vol. 162, BioOne, 2009, pp. 169–79.

@article{barber2009a,
  title = {Spatial variation in top-down direct and indirect effects on white oak (Quercus alba L.)},
  year = {2009},
  journal = {The American Midland Naturalist},
  pages = {169--179},
  publisher = {BioOne},
  volume = {162},
  author = {Barber, Nicholas A and Marquis, Robert J}
}