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