Perhaps you should try some spelling variations:
"certified network approximation algorithm" » "certified network approximation algorithms", "verified network approximation algorithm"
"modified parameter optimized algorithms" » "modified parameter optimized algorithm", "modified parameter optimizer algorithms", "modified parameter optimization 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 approximation algorithm") OR ("modified parameter optimized algorithms"))~.
• Removing quotes may allow a broader search: (( certified network approximation algorithm ) or ( modified parameter optimized algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("certified network approximation algorithm") or ("modified parameter optimized algorithms"))*.