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

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 algorithm"))~.
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