1. Perfect, W. (1787)Select cases in the different species of insanity. London: Rochester. P. 118.
2. Kraepelin, E. (1919)Dementia praecox and paraphrenia. New York: Robert E. Krieger (reprinted 1971). P. 240.
3. Bleuler, E. (1911)Dementia praecox or the group of schizophrenias. New York: International Universities Press (reprinted 1950). P. 343.