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2. 3. Harold G. Wolff, and Helen Goodell , "The Relation of Attitude and Suggestion to the Perception of and Reaction to Pain ," Proceedings of the Association for Research in Nervous and Mental Diseases, 23 , 1943 , p.434 .
3. 5. James D. Hardy, H. G. Wolff, and H. Goodell , Pain Sensations and Reactions , Baltimore: The Williams and Wilkins Company, 1954 , p.1 .