Perhaps you should try some spelling variations:
"modified objective location algorithmss" » "modified objective solution algorithm", "modified objective allocation algorithmss", "modified objective location algorithms"
"modified objective approximation algorithms" » "modified objective approximation algorithm"

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• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified objective location algorithmss") OR ("modified objective approximation algorithms"))~.
• Removing quotes may allow a broader search: (( modified objective location algorithmss ) or ( modified objective approximation algorithms ))~.
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