Paraphrasing
When the author's name appears in the sentence, it does not need to be repeated in the citation.
Example:
Recent literature has examined long-run price drifts following initial public offerings and other factors (Ritter 1991). Fisher (2009) reaches more or less the same conclusion.
Quotations
Example:
Several studies have shown that "F. oxysporum isolates collected as nonpathogenic or pathogenic to other hosts that have very similar or identical elongation factor 1α and mitochondrial small subunit genotypes as banana pathogens were shown to cause little or no disease on banana" (O'Donnell 1998, 2044).
More than one author
(Smith and Johnson 1998, 14)
(Smith, Johnson, and White 2001, 42)
More than three authors
(Smith et al. 1998, 203)
No author
(Plagiarism and You 2002, 142)