Improving measurement properties of the Patient Health Questionnaire-9 with rating scale analysis
Rehabilitation Psychology (2009) - Comment
pubmed: 19469610  doi: 10.1037/a0015529  issn: 0090-5550  issn: 1939-1544 

Ryan T. Williams, Allen W. Heinemann, Rita K. Bode, Catherine S. Wilson, Jesse R. Fann, Denise G. Tate