Perhaps you should try some spelling variations:
"modified robust optimization algorithms" » "modified robust optimisation algorithm", "modified robust estimation algorithms", "modified robust estimation algorithm"
"modified parameter approximation algorithms" » "modified parameters approximation algorithms"

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