Scholarly encyclopedias, like those listed on this page, can be very useful when you want to start understanding a new concept. Peer reviewed journal articles often focus on a narrow aspect of a topic; when you want to understand a topic more broadly, articles from reference books can be very useful. These function somewhat like Wikipedia, but with a higher degree of credibility and authority since the authors of these reference sources are often professors or other researchers with expertise on the topic.
Reference sources can be a helpful place to start researching a topic, because:
This page provides links to some specific reference sources on education topics as well as links to some searchable databases of reference ebooks. The Sage Knowledge database can be especially useful, as it includes many education related reference sources.