Perhaps you should try some spelling variations:
"modified coverage approximation algorithms" » "modified average approximation algorithms"
"modified based estimation algorithms" » "modified based estimation algorithm", "modified based optimization algorithms", "modified based optimisation algorithm", "modified pose estimation algorithms", "modified based investigation algorithms", "modified pulses estimation algorithms", "modified male estimation algorithms"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified coverage approximation algorithms\") OR (\"modified based estimation algorithms\"))~".
• Removing quotes may allow a broader search: (( modified coverage approximation algorithms ) OR ( modified based estimation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified coverage approximation algorithms") OR ("modified based estimation algorithms"))*.