Slota C, Ulrich C, Miller-Davis C, Baker K, Wallen G. Qualitative inquiry: a method for validating patient perceptions of palliative care while enrolled on a cancer clinical trial. BMC Palliat Care. 2014 Sep 5;13:43. doi: 10.1186/1472-684X-13-43.
Hartman M, Bolton E, Fehnel SE. Accounting for age differences on the Wisconsin Card Sorting Test: decreased working memory, not inflexibility. Psychol Aging. 2001 Sep 1;16(3):385-99.