Perhaps you should try some spelling variations:
"racial difference equations" » "racial differential equations", "racial differential equationss", "racial differences equations", "facial difference equations", "social difference equations"
"racial difference equation" » "racial differential equation", "racial differential equations", "racial differences equation", "facial difference equation", "social difference equation"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("racial difference equations") OR ("racial difference equation"))*.
• Removing quotes may allow a broader search: (( racial difference equations ) or ( racial difference equation ))*.