Perhaps you should try some spelling variations:
"partial differential equation" » "partial differential equations", "partial difference equations"
"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 difference equationss"))*.
• Removing quotes may allow a broader search: (( partial differential equation ) or ( partial difference equationss ))*.