With the name-date format you can use the author's name in the sentence or tack it on at the end. In either case the date goes immediately after the author’s name. If there are two co-authors, name both of them:

     Smith and Jones (1947) found that breast cancer . . . .

     and

     The mechanism of natural selection was first described in the 19th century (Darwin 1859).
     {Note that the period goes after the citation.}

If there are three or more co-authors only list the first one followed by "et al." (latin, et alii, for "and others"):

     Filebert, et al. (1974) studied the predatory behavior of . . . .

Occasionally it may be necessary to cite a paper that you read about, but could not read yourself because it was unavailable. In that case, use the following format to indicate where you got the information. Note that both Lamark and Smith should be cited in full in the Literature Cited section.

     Lamark (1783) argued that species changed over time (cited in Smith 1988).

Do you have to cite an author after every sentence? No, but it should be often enough that the reader is never in doubt about where the information came from. That might be as little as one citation per paragraph. Use your judgment.

Literature Cited

Blem, C. R. 1975. Geographic variation in wing-loading of the house sparrow. Wilson  
     Bulletin 87:543-549. {After the name of the journal comes the Volume:Page
     Numbers. Do not include the issue # except for magazines that do not
     number all pages in a volume sequentially, as in the next example.}

Bigg, J. T. 1983. Chaos theory. Scientific American 75(3): 24-33.

Charnov, E. L. 1976. Optimal foraging: attack strategy of a mantid. American Naturalist
     110:141-151. {Only the first word of the title is capitalized.}

Craig, R.B., D.L. DeAngelis, and K.R. Dixon. 1979. Long- and short-term dynamic
     optimization models with application to the feeding strategy of the loggerhead shrike.
     American Naturalist 113:31-51. {List all authors. Do not use "et al." here.}

Daly, M, L. F. Jacobs, M. I. Wilson, and P. R. Behrends. 1992. Scatter hoarding by
     kangaroo rats (Dipodomys merriami) and pilferage from their caches. Behavioral
     Ecology 3:102-111. {Scientific names must be italicized or underlined.}

Orians, G. H., and N. E. Pearson. 1979. On the theory of central place foraging. Pages
     155-177 in D. J. Horn, R. D. Mitchell, and G. R. Stairs, eds. Analysis of ecological
     systems. Ohio State University Press, Columbus. {citation for article in an edited
     book}

{List papers alphabetically by author first and then by date}

Post, D. 1991a. An analysis of factors affecting cache use behavior by eastern woodrats
     (Neotoma floridana). Ph.D. Dissertation, Kansas State University, Manhattan, 91pp.

-------. 1991b. Change in nutrient content of foods stored by eastern woodrats
     (Neotoma floridana). Journal of Mammalogy 73:835-839. {Note, two papers by
     the same author(s) published in the same year are distinguished by lower case
     letters both here and where you cite them in your paper.}

Post, D., and O.J. Reichman. 1991. Effects of food perishability, distance, and competitors
     on caching behavior by eastern woodrats. Journal of Mammalogy 72:513-517.

Post, D. M., O. J. Reichman, and D. E. Wooster. 1993. Characteristics and significance of
     the caches of eastern woodrats (Neotoma floridana). Journal of Mammalogy
     74:688-692.

{Examples of Book Citations:}

Spector, W. S. (ed.) 1956. Handbook of biological data. W. B. Saunders Co., Philadelphia.

Stephens, D. W., and J. R. Krebs. 1986. Foraging theory. Princeton University Press,
     Princeton, N. J.

Vander Wall, S.B. 1990. Food hoarding in animals. University of Chicago Press, Chicago.  

In the literature cited section of some papers journal names are abbreviated. There are several rules to keep in mind here. First, never abbreviate one-word journal names like "Ecology" or "Nature." Second, be consistent, either abbreviate all journal names (with the exception mentioned above) or do not abbreviate any of them. Finally, use the standard abbreviation for each journal, do not make up your own.