Perhaps you should try some spelling variations:
"modified coverage approximation algorithms" » "modified average approximation algorithms"
"modified learning predators algorithm" » "modified learning predation algorithm", "modified marine predators algorithm", "mobile learning predators algorithm", "modified caging predators 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 learning predators algorithm") or ("modified coverage approximation algorithms"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified learning predators algorithm") OR ("modified coverage approximation algorithms")).
• Removing quotes may allow a broader search: (( modified learning predators algorithm ) or ( modified coverage approximation algorithms )).
• Adding a wildcard symbol may retrieve word variants: (("modified learning predators algorithm") or ("modified coverage approximation algorithms"))*.