The key database for education literature is ERIC (linked below.) While you can use any keywords that describe the topic, using the terms that ERIC uses to describe topics (called descriptors) can make a big difference in finding useful articles and other publications. These terms can be identified using the ERIC Thesaurus.
Please note that in order to locate older articles published, scholarly research often requires searching with phrases or words that are now inappropriate, such as "mental retardation."
For legal issues, consider searching:
Combining appropriate legal terms with appropriate terms for special needs students using the AND command will provide more relevant articles, e.g.,