Reference books, like encyclopedias and dictionaries, are a good first source to use when research a new topic. Encyclopedias, like the examples below, give you an overview of your topic and its history, and will lead you to additional sources.
Encyclopedia databases:
Education Today: Concepts, Issues, Policies and Politics by 
The Praeger International Handbook of Special Education [3 Volumes] by 
Encyclopedia of Education
Encyclopedia of Diversity and Social Justice by 
Encyclopedia of Race and Racism
Handbook of Social and Emotional Learning
The Encyclopedia of Middle Grades Education
Psychology of Classroom Learning: An Encyclopedia
