Perhaps you should try some spelling variations:
differentes situations » different situations, difference equations
differential equation » differential equations, difference equations
difference equation » difference equations, differential equations

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 ((differentes situations) OR (((difference equation) OR (differential equation)))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "racial ((differentes situations) or (((difference equation) OR (differential equation))))".
• Adding a wildcard symbol may retrieve word variants: racial ((differentes situations) or (((difference equation) OR (differential equation))))*.