When searching for the databases, you can limit your search to the subject of special education. For a broad search try using
"special education" OR "inclusive education"
Also look at the subject headings for each database. Use the Thesaurus in ERIC or PsycINFO to determine your search terms. Other databases have similar directories. Look at MeSH in Medline and PubMed.
Use a truncation symbol, such as ? or *, to find several words with the same root, for example:
child* (finds child, children, and childhood)
behavio?r (finds behavior and behaviour)