^Pratt, J. G., Rhine, J. B., Smith, B. M., Stuart, C. E., & Greenwood, J. A. (1940). Extra-Sensory Perception after Sixty Years. New York, NY, US: Henry Holt.
^فيكتور شتينجر. (1990). Physics and Psychics: The Search for a World Beyond the Senses. Prometheus Books. pp. 171–174.
^Hansel, C. E. M. (1980). ESP and Parapsychology: A Critical Re-Evaluation. Prometheus Books. pp. 125–140.
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