I am using this site in my Foundations of Instructional Technology class. This is a good site for use in not only that class but - Instructional Design, Learning Theories, or other courses that require considering how design and theory are related. The site provides a very good overview. I may not agree with all conclusions within the paper, but the overall quality is good and the paper is well thought out.
Since it is essentially a paper, it is easy to use. All of the links work.