Below you there are some links to relevant databases/websites for literature research in mathematics education.

• UB Greifswald is important as the local university library (get books and access to online ressources)
• Google Scholar is an important database für literature research. A large number of links, references, and download options are displayed

The following two sources are of interest for literature research in mathematics education:

• Collection of journals by Jürgen Roth: On his website, Jürgen Roth offers an overview of (almost) all the most important (inter-)national journals. Most of them also include an overview of previous issues.
• Collected of LINKs by Jürgen Roth: Jürgen Roth also has a collection of selected links on mathematics education.

• Fachportal Pädagogik: The "Fachportal Pädagogik" is a meta search engine that searches a total of 21 mostly german data sources.
• ERIC offers an english database.