“Those whose standards are high beyond reach or reason, people who strain compulsively and unremittingly toward impossible goals and who measure their own worth entirely in terms of productivity and accomplishment. For these people, the effort for excellence is self-defeating.” (Burns, 1980, p. 34). 
 “Setting of excessively high standards for performance accompanied by overly critical self-evaluation” 
(Frost et.al, 1990, p. 450). 
Hewitt and Flett (1991):
 Self-oriented perfectionism (unrealistic standards and perfectionistic motivation for the self)
 Other-oriented perfectionism (unrealistic standards and perfectionistic motivations for others)
 Socially prescribed perfectionism (the belief that significant others expect oneself to be perfect).

Burns, D. (1980). The perfectionist’s script for self defeat.(1980). Psychology Today, 34-51.
Frost, R. O., Marten, P., Lahart, C., & Rosenblate, R. (1990). The dimensions of perfectionism. Cognitive therapy and research, 14(5), 449-468
Hewitt, P.L., Flett, G.L., Turnball-Donovan, W., & Mikhail,. S.F. (1991). The multidimensional perfectionism scale: Reliability, validity and psychometric properties in psychiatric samples. Psychological Assessment, 3, 464-468.

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