Perhaps you should try some spelling variations:
"modified rough approximation algorithm" » "modified rough approximation algorithms", "modified rough approximations algorithm", "modified one approximation algorithm"
"modified invasive estimation algorithms" » "modified invasive estimation algorithm", "modified invasive optimization algorithms", "modified invasive optimisation algorithm", "modified invasive ventilation algorithms", "modified passive estimation algorithms"

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• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"modified invasive estimation algorithms\") OR (\"modified rough approximation algorithm\"))~".
• Removing quotes may allow a broader search: (( modified invasive estimation algorithms ) OR ( modified rough approximation algorithm ))~.
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