Perhaps you should try some spelling variations:
"racial differentes situations" » "racial different situations", "racial difference situations", "crucial differences situations", "social differences situations"
"racial differences equations" » "racial difference equation", "racial differential equations", "racial differences variations", "regional differences equations", "national differences equations"
"potential difference equations" » "potential differential equations"

Try widening your search to All Fields.

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