Perhaps you should try some spelling variations:
"modified coverage approximation algorithms" » "modified average approximation algorithms"
"modified early solution algorithm" » "modified early evolution algorithm", "modified early convolution algorithms", "modified early evolutionary algorithm", "modified male solution algorithm", "modified near solution algorithm", "modified nacl solution 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 coverage approximation algorithms") or ("modified early solution algorithm"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified coverage approximation algorithms") OR ("modified early solution algorithm"))*.
• Removing quotes may allow a broader search: (( modified coverage approximation algorithms ) or ( modified early solution algorithm ))*.