Perhaps you should try some spelling variations:
"modified dfverage approximation algorithms" » "modified average approximation algorithms", "modified _verage approximation algorithms", "modified adamverage approximation algorithms", "modified bi1verage approximation algorithms"
"modified df evolutionary algorithm" » "modified df evolution algorithm", "modified df solution algorithm", "modified _ evolutionary algorithm", "modified adam evolutionary algorithm", "modified bi1 evolutionary algorithm"

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified dfverage approximation algorithms") or ("modified df evolutionary algorithm"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified dfverage approximation algorithms") OR ("modified df evolutionary algorithm")).
• Removing quotes may allow a broader search: (( modified dfverage approximation algorithms ) or ( modified df evolutionary algorithm )).
• Adding a wildcard symbol may retrieve word variants: (("modified dfverage approximation algorithms") or ("modified df evolutionary algorithm"))*.