N. Calvo Piñero, X. Caseras Vives, F. Gutiérrez Ponce de León, and R. Torrubia Beltri, “Spanish version of the Personality Diagnostic Questionnaire-4+ (PDQ-4+)”, Actas Esp Psiquiatr, vol. 30, no. 1, pp. 7–13, Jan. 2002.