Defining Scholarly Sources
A scholarly source is one that meets the following criteria:

• Authority
• Are the author or authors identified?
• Do they have scholarly credentials, or credentials within the appropriate field of expertise?
• Structure
• Do the authors cite the works from which they drew inspiration and/or information?
• Do illustrations relay vital information (charts, etc.), rather than simply making the article or book more attractive?
• Content
• Is the intended audience a group of scholars or a group of people who have expertise in a particular trade or profession?
• Is the language is specific to the discipline or intended for large audiences?

Don't think of a scholarly source as something that's been stamped SCHOLARLY SOURCE. Think of it as a resource which is authoritative, which is structured and presented professionally, and which has content and style appropriate to a scholarly rather than a popular audience.

Sometimes some of these criteria will be more important than others. For instance, a trade magazine on the advertising industry with an article on the marketing of beer to minors may be appropriate for a class in mass communication or marketing, but inappropriate for a class on the biological effects of alcohol on underage drinkers. While the publication is intended for people in a particular trade, and not mainly for scholarly consumption, the information in the magazine can be useful to students of advertising, rhetoric, and marketing.

Types of Sources

Primary Sources	Primary Sources are original materials which have not been interpreted or condensed. They represent original observations or documentation of occurrences (such as interviews, conducting a survey, carrying out a laboratory experiment, letters, diaries, or journals) and include statistical data, historical documents, and works of literature and art.
Secondary Sources	Secondary Sources provide information or analysis of primary sources. They often take primary source data and modify, select, or arrange the material for a specific audience. Sometimes, they try to represent material in a certain light for rhetorical purpoases. They include books or articles about political issues, historical events, scientific debates, or literary works. Secondary sources can be reports, findings, or summaries of other researchers on a topic, or they can be scholarly analysis of primary source material.
Tertiary Sources	Tertiary Sources provide information collected from primary and secondary sources, and include textbooks and almost all types of reference works, such as dictionaries, encyclopedias, reviews, biographical sources, fact-books, and almanacs.