Perhaps you should try some spelling variations:
"modified coverage approximation algorithms" » "modified average approximation algorithms"
"modified level production algorithms" » "modified level predation algorithm", "modified level evolution algorithm", "modified level solution algorithm", "modified element production algorithms", "modified global production algorithms", "modified legal protection 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 coverage approximation algorithms") OR ("modified level production algorithms"))~.
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