Perhaps you should try some spelling variations:
"racial differences equations" » "racial difference equations", "racial differentes situations", "racial differences variations", "regional differences equations", "national differences equations", "facial differences equations", "social differences equations", "rational differences equations"
"racial differential equations" » "radial differential equations", "rail differential equations", "practical differential equations"
"racial difference equation" » "racial difference equations", "racial differential equation", "facial difference equation", "social difference equation", "rational 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 differences equations") OR ("racial differential equations"))) OR ("racial difference equation"))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"racial differences equations\") OR (\"racial differential equations\"))) or (\"racial difference equation\"))*".
• Removing quotes may allow a broader search: (((( racial differences equations ) OR ( racial differential equations ))) or ( racial difference equation ))*.