Academic Search Complete is the world's most valuable and comprehensive scholarly, multi-disciplinary full-text database, with more than 8,500 full-text periodicals, including more than 7,300 peer-reviewed journals.
The PsycINFO®, database, American Psychological Association’s (APA) renowned resource for abstracts of scholarly journal articles, book chapters, books, and dissertations, is the largest resource devoted to peer-reviewed literature in behavioral science and mental health.
Education Research Complete is the definitive online resource for education research. Topics covered include all levels of education from early childhood to higher education, and all educational specialties, such as multilingual education, health education, and testing.
You can search Google Scholar using the citations for existing works and sometimes you will find a full-text copy of the article.
Google Scholar also allows you to "cite forward" its articles; in other words, you can see who has cited a particular article, to determine further developments in this line of research and find additional related sources.