A Secondary source is a work written about an event or person after it has taken place. Some examples:
In Academe, we are especially interested in a specific type of secondary source: Peer Reviewed Publications.
But what's the difference between scholarly, peer reviewed, popular, or refereed?
Scholarly: A source written by an expert, but not subjected to the peer review process.
Example: magazine articles (if written by expert), public presentations, reviews, opinion pieces.
Refereed: Academic work that has some level of vetting, usually by an editor or panel.
Example: Conference papers, journal articles that are approved by an editor but not external reviewers.
NOTE: refereed is often used interchangeably with Peer Reviewed by databases, but it isn't always the same.
Popular: Written for a wide readership. May or may not be written by a subject expert.
Examples: newspaper or magazine, popular press books, websites.
Peer Reviewed: Academic books and articles written by a specialist, reviewed by other experts, and published by an academic press.
Examples: Articles in academic journals, some conference papers, books published by university presses.