Perhaps you should try some spelling variations:
"modified coverage approximation algorithms" » "modified average approximation algorithms"
"modified seird classification algorithm" » "modified seizure classification algorithm", "modified blind classification algorithm", "modified using classification algorithm", "modified near classification 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 seird classification algorithm"))~.
• Removing quotes may allow a broader search: (( modified coverage approximation algorithms ) or ( modified seird classification algorithm ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified coverage approximation algorithms") or ("modified seird classification algorithm"))*.