Perhaps you should try some spelling variations:
"modified network optimization algorithms" » "modified network optimisation algorithm", "modified network estimation algorithms", "modified network estimation algorithm", "certified network optimization algorithms", "defined network optimization algorithms", "modified near optimization algorithms"
"machines using method algorithm" » "machines using mom algorithm", "machinery using method algorithm", "machines nursing methods algorithm", "machines focusing method algorithm", "machines using metal algorithm"

Try widening your search to All Fields.

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