American Psychological Association (APA) style is primarily used for research in psychology, education and social sciences. Document quotes, paraphrasing, summarizations and source material are within parenthetical citations, which correspond to the bibliography entries. All parenthetical entries have page numbers listed after the authors' names. For the first reference, list all authors' names within parentheses at the end of the sentence. Succeeding references only require the first author's name. Groups or organizations are referred to by the group's name, though long names can be abbreviated in subsequent references. For works with no author, you can use the title or a few key words from the title.
Modern Language Association (MLA) is used mainly to cite sources in literature, arts and humanities research. In-text citations for quotes, summarizations and paraphrases are placed in parentheses at the end of the sentence containing the cited material, include the page numbers and correspond with the bibliography entries. For single authors, the last name is placed in the parentheses; all last names are listed for multiple authors. Organizations are listed by their full name or an abbreviated title that is easily identifiable. Works with no authors are listed by the italicized title within the parentheses.
The Chicago Manual of Style is used citing materials published in books, periodicals and other publications, as well as for humanities research. Citations are made through footnotes (at the bottom of the page) or endnotes (at the end of the paper), and are entered in numerical order. Assigned citation numbers are listed at the end of the clause or the sentence containing the cited material and match the footnote or endnote numbers. The first citation for each source includes the entire bibliographic entry. Use the Latin term ibid and a page number when citing the same source several times consecutively. Subsequent citations from a consecutive source require only the author's last name or an abbreviated organization name and the page number. Include an alphabetical bibliography at the end of the paper.
Turabian citations can be used for any academic research paper, though it is mainly used for physical, natural and social sciences. The Turabian style consists of two systems of documentation. The first is a footnote or endnote with bibliography style (like the Chicago Manual of Style). The second is the parenthetical citations with bibliography style (like APA). While being essentially the same format as the Chicago and APA styles, they have been modified somewhat for students to use by making the information required in the list of references more concise.