Perhaps you should try some spelling variations:
"modified notion approximation algorithms" » "modified network approximation algorithms", "modified time approximation algorithms", "modified one approximation algorithms"
"modified charging station algorithm" » "modified caging station algorithm", "modified carbon station algorithm", "modified charging estimation algorithm", "modified charging solution algorithm", "modified charging estimation 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 notion approximation algorithms") OR ("modified charging station algorithm"))~.
• Removing quotes may allow a broader search: (( modified notion approximation algorithms ) or ( modified charging station algorithm ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified notion approximation algorithms") or ("modified charging station algorithm"))*.