Perhaps you should try some spelling variations:
metaheuristic approach » heuristic approach
naturalistic approach » pluralistic approach, heuristic approach, realistic approach
futuristic approach » heuristic approach, humanistic approach, heuristic approaches

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: ((naturalistic approach) OR (((futuristic approach) OR (metaheuristic approach)))).
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• Adding a wildcard symbol may retrieve word variants: ((naturalistic approach) or (((futuristic approach) OR (metaheuristic approach))))*.