Perhaps you should try some spelling variations:
25 psychological » 5 psychological, 2 psychological, 21 psychological
15 psychological » 5 psychological, 1 psychological, 12 psychological
2f congresses » _ congresses, 6 congresses, 1 congresses

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• The words AND, OR and NOT may confuse the search; try adding quotes: "%22science %((25 psychological) OR (15 psychological)) aspects %2f congresses%22".
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