Perhaps you should try some spelling variations:
"modified network approximation algorithm" » "modified network approximation algorithms", "certified network approximation algorithm", "defined network approximation algorithm", "modified near approximation algorithm"
"modified parameters estimation algorithms" » "modified parameter estimation algorithms", "modified parameter estimates algorithms", "modified parameter optimization algorithms", "modified parameters estimation algorithm", "modified parameters optimization algorithms", "modified parameters optimisation algorithm"

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