Wikimedia
Wikipedia: Perfect Competition
This site provides a clear description of the requirements and conditions needed in a market for it to be labeled a perfectly competitive market. The topics of allocative efficiency and productive efficiency are also addressed.
Other
South Western Learning: Econ News: Comparative Statics: Perfect Competition
This site offers economics-based newspaper headlines and asks follow-up questions based on supply and demand in a perfectly competitive market.
Other
South Western Learning: Econ News: Perfect Competition
This site offers a variety of economics-related newspaper headlines in perfectly competitive markets, and each headline offers discussion questions related to that topic.
Tutor2u
Tutor2u: Perfect Competition Introduction
This website describes the conditions of a "perfectly competitive" market structure, and the obstacles that the individual firm in this market will face.