Perhaps you should try some spelling variations:
"different evaluations" » "different evaluation", "different valuations", "different evolutions"
"differental equations" » "differential equations1", "diflferential equations", "diferential equations"
"different equations" » "differences equations", "differenced equations", "different regulations"

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