Perhaps you should try some spelling variations:
"certified network approximation algorithm" » "certified network approximation algorithms", "verified network approximation algorithm"
"modified objective allocation algorithm" » "modified objective estimation algorithm", "modified objective evolution algorithm", "modified objective predation algorithm"

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

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