Perhaps you should try some spelling variations:
"modified a classification algorithm" » "modified _ classification algorithm", "modified gas classification algorithm", "modified image classification algorithm", "modified df classification algorithm", "modified adam classification algorithm"
"modified average approximation algorithms" » "modified _verage approximation algorithms", "modified dfverage approximation algorithms", "modified adamverage approximation algorithms", "modified coverage approximation 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 a classification algorithm") OR ("modified average approximation algorithms"))~.
• Removing quotes may allow a broader search: (( modified a classification algorithm ) or ( modified average approximation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified a classification algorithm") or ("modified average approximation algorithms"))*.