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

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• Performing a fuzzy search may retrieve terms with similar spellings: (( modified staffing optimization algorithm ) or ( modified objective optimization algorithms ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( modified staffing optimization algorithm ) OR ( modified objective optimization algorithms )).
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