Dissertations & Theses are excellent resources to find information about theories. Chapters devoted to the "literature review", "theoretical models", and the bibliograpy are rich in content that might be useful for you.
It includes dissertation indexes (1861-present), dissertation abstracts (1980-present) and theses abstracts (1988-present). The database offers full text for most of the dissertations added since 1997 and strong retrospective full text coverage for older graduate works.
NDLTD is an international organization that, through leadership and innovation, promotes the adoption, creation, use, dissemination and preservation of electronic theses and dissertations.
