Perhaps you should try some spelling variations:
"partial differential equation" » "partial difference equations"
"partial differential equations" » "partial difference equationss"
"partial difference equationss" » "partial difference equations", "partial difference equation", "partial differences equations", "potential difference equationss", "racial differences equationss"

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