1. Altamura AC, Carta MG, Tacchini G, Musazzi A, Pioli MR (1998) Prevalence of somatoform disorders in a psychiatric population: an Italian nationwide survey. Eur Arch Psy Clin N 248:267–271
2. American Psychiatric Association (1980) Diagnostic and Statistical Manual of Mental Disorders (3rd edn) (DSM–III). Washington, D. C.: American Psychiatric Press
3. American Psychiatric Association (1987) Diagnostic and Statistical Manual of Mental Disorders (3rd edn, revised) (DSM–III–R). Washington, D. C.: American Psychiatric Press
4. American Psychiatric Association (1994) Diagnostic and Statistical Manual of Mental Disorders (4rd edn) (DSM–IV). Washington, D. C.: American Psychiatric Press
5. Bair MJ, Robinson RL, Katon W, Kroenke K (2003) Depression and pain comorbidity—a literature review. Arch Intern Med 163:2433–2445