When you quote, paraphrase, summarize, or otherwise refer to the work of another, you are required to cite its source, either with a parenthetical citation, footnote, or endnote. Not to do so is considered plagiarism. Anything you write or create that uses or refers to the ideas of another person must be cited properly, this includes:
You do not need to cite common knowledge. For example, you do not need to cite the fact that Thomas Jefferson was the third president of the United States, but you would need to cite your source for the types of crops he grew at Monticello.
Before starting your research, identify the appropriate citation style according to the academic discipline and/or media format. Check with your instructor about which style you should use.
The Chicago Manual Style (CMS) is the most commonly used method of source documentation in history courses, although some humanities courses may also require this method. Unlike the parenthetical (in-text) citations used in the APA and MLA styles, CMS uses footnotes, along with a bibliography. This Chicago Manual Style Guide provides examples of both footnote/endnote and bibliographical citations for the most commonly used print, online, and media sources. For a more comprehensive explanation, please consult The Chicago Manual of Style 16th ed. available in the Reference section of Long Library (Call # R 808 C53m 2003).
Other helpful links:
“Chicago Manual of Style 'Quick Guide'" from the Chicago Manual of Style Online
Explanation and examples of the Chicago Manual of Style from OWL: Purdue Online Writing Lab.
Video Tutorial: Chicago Manual of Style: An Overview