1. American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, DSM-IV-TR. Washington, American Psychiatric Association, 2000.
2. Diagnosis and Classification of Psychopathology: Challenges to the Current System and Future Directions
3. Toward a Scientific Psychiatric Nosology
4. Kraepelin E: Lectures on clinical psychiatry, ed 3. New York, William Wood, 1917.
5. Krueger RF: Psychometric perspectives on comorbidity; in Helzer JE, Hudziak JJ (eds): Defining psychopathology in the 21st century. DSM-V and beyond. Washington, American Psychiatric Publishing, 2002, pp 41-54.