Perhaps you should try some spelling variations:
"racial differences equation" » "racial differences equations", "racial differenced equations", "racial differences education", "regional differences equation", "national differences equation", "facial differences equation", "social differences equation", "rational differences equation"
"racial difference equation" » "racial difference equations", "racial differential equation", "racial differential equations", "facial difference equation", "social difference equation", "rational difference equation"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"racial difference equation\") OR (\"racial differences equation\"))".
• Removing quotes may allow a broader search: (( racial difference equation ) OR ( racial differences equation )).
• Adding a wildcard symbol may retrieve word variants: (("racial difference equation") OR ("racial differences equation"))*.