Perhaps you should try some spelling variations:
"modified allocation approximation algorithms" » "modified allocation optimization algorithms"
"modified caging optimization algorithms" » "modified caging optimisation algorithm", "modified caging estimation algorithms", "modified caging estimation algorithm", "modified staffing optimization 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 caging optimization algorithms") OR ("modified allocation approximation algorithms"))~.
• Removing quotes may allow a broader search: (( modified caging optimization algorithms ) or ( modified allocation approximation algorithms ))~.
• Adding a wildcard symbol may retrieve word variants: (("modified caging optimization algorithms") or ("modified allocation approximation algorithms"))*.