APA   Click to copy
Watkins Jr, J. E., Cardel{\'u}s, C., Colwell, R. K., & Moran, R. C. (2006). Species richness and distribution of ferns along an elevational gradient in Costa Rica. American Journal of Botany, 93, 73–83.

Chicago/Turabian   Click to copy
Watkins Jr, James E, Catherine Cardel{\'u}s, Robert K Colwell, and Robbin C Moran. “Species Richness and Distribution of Ferns along an Elevational Gradient in Costa Rica.” American Journal of Botany 93 (2006): 73–83.

MLA   Click to copy
Watkins Jr, James E., et al. “Species Richness and Distribution of Ferns along an Elevational Gradient in Costa Rica.” American Journal of Botany, vol. 93, Botanical Society of America, 2006, pp. 73–83.

@article{watkins2006a,
  title = {Species richness and distribution of ferns along an elevational gradient in Costa Rica},
  year = {2006},
  journal = {American Journal of Botany},
  pages = {73--83},
  publisher = {Botanical Society of America},
  volume = {93},
  author = {Watkins Jr, James E and Cardel{\'u}s, Catherine and Colwell, Robert K and Moran, Robbin C}
}