The mechanics of citing sources will vary from style to style, but there are two primary methods of giving citations: parenthetical (in-text) references and notes. Although most documentation styles provide guidelines for both in-text references and notes, each is generally identified with one or the other.

Parenthetical references

Systems of parenthetical reference have become popular in the past twenty years or so. Their greatest strength from the standpoint of the reader is that they don't obligate the reader to search for citations at the bottom of the page or at the end of the document; all necessary information is located in the text, immediately following the quotation or reference. From the standpoint of the writer, parenthetical reference styles are much easier than notes to format and keep track of (although most word processors will handle this automatically).

Parenthetical references work in conjunction with the list of sources that appears at the end of your document. That is, the information that appears in parentheses after a quotation or reference allows the reader to turn to the list of sources and identify which one is being cited. Thus, if a particular author has more than one entry in the list of sources, your parenthetical reference must give enough information to allow the reader to identify which work is being cited. This may involve including the year of publication, or a shortened version of the title, or both.

The information provided in the parenthetical reference varies from style to style. Because the chronology of previous research is important in evaluating its usefulness, the APA style requires the date to be included with the author's name. Other styles, such as the MLA style, require only the page number for quotations (as long as there will be no confusion as to which work is being cited).