Perhaps you should try some spelling variations:
"certified network optimization algorithms" » "certified network optimisation algorithm", "certified network estimation algorithms", "certified network estimation algorithm", "verified network optimization algorithms"
"modified notion approximation algorithms" » "modified network approximation algorithms", "modified time approximation algorithms", "modified one approximation algorithms"

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: (("certified network optimization algorithms") OR ("modified notion approximation algorithms"))~.
• Removing quotes may allow a broader search: (( certified network optimization algorithms ) or ( modified notion approximation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("certified network optimization algorithms") or ("modified notion approximation algorithms"))*.