Perhaps you should try some spelling variations:
"modified df approximation algorithm" » "modified _ approximation algorithm", "modified one approximation algorithm", "modified time approximation algorithm", "modified adam approximation algorithm", "modified bi1 approximation algorithm"
"modified network approximation algorithms" » "certified network approximation algorithms", "defined network approximation algorithms", "modified near approximation algorithms"

Try widening your search to All Fields.

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

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