Perhaps you should try some spelling variations:
"differential equation" » "differential equations", "difference equations"
"differenced equations" » "difference equations", "difference equation", "differental equations"
"differences equations" » "difference equations", "difference equation", "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 ((("differenced equations") OR ((("differenced equations") OR ("differences equations")))))).
• Removing quotes may allow a broader search: (( differential equation ) or ((( differenced equations ) or ((( differenced equations ) or ( differences equations )))))).
• Adding a wildcard symbol may retrieve word variants: (("differential equation") or ((("differenced equations") or ((("differenced equations") or ("differences equations"))))))*.