Perhaps you should try some spelling variations:
"certified network approximation algorithm" » "certified network approximation algorithms", "verified network approximation algorithm"
"modified bayesian optimisation algorithm" » "modified bayesian optimization algorithms", "modified bayesian estimation algorithm", "modified bayesian estimation algorithms", "modified bayesian optimization algorithm"

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• If you are trying to use Boolean operators, they must be ALL CAPS: (("modified bayesian optimisation algorithm") OR ("certified network approximation algorithm"))~.
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