ERIC is one of the core education databases out there in the discipline. It contains peer reviewed and trade articles, dissertations and reports.
You can limit your search here to look at just literature reviews or dissertations. No one said you can't use someone else's lit review to find articles for your own research! These are gold mines if you can find the right one.
ERIC, the Educational Resource Information Center, provides access to education literature and resources. The database provides access to information from journals included in the Current Index of Journals in Education and Resources in Education Index. ERIC provides full text of more than 2,200 digests along with references for additional information and citations and abstracts from over 1,000 educational and education-related journals.
Lit searches need to be comprehensive. No matter how big one database is, other databases will have different coverage of journals/publications so to say you've truly scoured the literature for information on your topic, you'll want to try multiple databases. Especially when it comes to multidisciplinary topics!
Education Source is a good database to include for additional coverage in education.
The ProQuest Dissertations & Theses database (PQDT) indexes over 2.4 million dissertations and theses included from around the world nearly one million are available in full text. Each dissertation published since July 1980 includes a 350-word abstract written by the author. Master's theses published since 1988 include 150-word abstracts. Bibliographic citations are available for dissertations dating from 1637, and more than 65,000 new citations are added to the database every year.
Web of Science is a great source for scholarly materials. Don't worry! It's not just for science!
You may want to try using the Cited Reference Search. This will let you take a good article that you know about already, and search for all the articles that have cited that article! Really great way to move forward in time in a subject.
At this level of research, you can't be limited to what we happen to have in the collection. Don't get me wrong, we've got a great one, but we can't be expected to have everything in the world!
WorldCat will let you search the collections of libraries all over the world. It's also integrated with our interlibrary loan system, so if you find something that you want you can click on the Request through ILL button and have our ILL form filled out automatically.
One thing that's really important when you're gathering this much research is keeping track of it all!
Citation management tools give you a place to store and organize all those references you pull from databases, catalogs. They even help you write your paper by properly formatting the citations in your paper.
Check out this page for tools that you can use. I can assist you with RefWorks related questions.