Perhaps you should try some spelling variations:
"modified network optimization algorithms" » "modified network optimisation algorithm", "modified network estimation algorithms", "modified network estimation algorithm", "certified network optimization algorithms", "defined network optimization algorithms", "modified near optimization algorithms"
"modified invasive approximation algorithms" » "modified passive 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: (("modified invasive approximation algorithms") OR ("modified network optimization algorithms"))~.
• Removing quotes may allow a broader search: (( modified invasive approximation algorithms ) or ( modified network optimization algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified invasive approximation algorithms") or ("modified network optimization algorithms"))*.