Perhaps you should try some spelling variations:
"modified adaptive approximation algorithms" » "modified time approximation algorithms", "modified passive approximation algorithms"
"defined network estimation algorithms" » "defined network estimation algorithm", "defined network optimization algorithms", "defined network optimisation algorithm"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified adaptive approximation algorithms") OR ("defined network estimation algorithms"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified adaptive approximation algorithms\") OR (\"defined network estimation algorithms\"))".
• Removing quotes may allow a broader search: (( modified adaptive approximation algorithms ) OR ( defined network estimation algorithms )).
• Adding a wildcard symbol may retrieve word variants: (("modified adaptive approximation algorithms") OR ("defined network estimation algorithms"))*.