Jonathan D Huppert, Apfeldorf, William J, and Smith, Thomas E. 2002. “Use Of Self-Report Measures Of Anxiety And Depression In Outpatients With Schizophrenia: Reliability And Validity”. Journal Of Psychopathology And Behavioral Assessment, 24, Pp. 275–283. https://link.springer.com/article/10.1023/A:1020783101092.