Perhaps you should try some spelling variations:
"modified staffing optimization algorithmss" » "modified staffing optimization algorithms", "modified staffing optimisation algorithm", "modified staffing estimation algorithms", "modified caging optimization algorithmss"
"modified objective approximation algorithms" » "modified objective approximation algorithm"

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("modified staffing optimization algorithmss") or ("modified objective approximation algorithms"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified staffing optimization algorithmss") OR ("modified objective approximation algorithms")).
• Removing quotes may allow a broader search: (( modified staffing optimization algorithmss ) or ( modified objective approximation algorithms )).
• Adding a wildcard symbol may retrieve word variants: (("modified staffing optimization algorithmss") or ("modified objective approximation algorithms"))*.