Perhaps you should try some spelling variations:
"differential equation" » "differential equations"
"difference equationss" » "difference equation", "differenced equations", "difference equations0.4", "differential equationss"
"differences equations" » "difference equation", "differential equations", "differentes situations"
"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: (((("differential equation") OR ("difference equations"))) OR ((("difference equationss") OR ("differences equations")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"differential equation\") OR (\"difference equations\"))) or (((\"difference equationss\") or (\"differences equations\"))))".
• Removing quotes may allow a broader search: (((( differential equation ) OR ( difference equations ))) or ((( difference equationss ) or ( differences equations )))).
• Adding a wildcard symbol may retrieve word variants: (((("differential equation") OR ("difference equations"))) or ((("difference equationss") or ("differences equations"))))*.