Perceived helpfulness of treatment for generalized anxiety disorder: a World Mental Health Surveys report oleh Dan J. Stein, Alan E. Kazdin, Ayelet Meron Ruscio, Wai Tat Chiu, Nancy A. Sampson, Hannah N. Ziobrowski, Sergio Aguilar-Gaxiola, Ali Al-Hamzawi, Jordi Alonso, Yasmin Altwaijri, Ronny Bruffaerts, Brendan Bunting, Giovanni de Girolamo, Peter de Jonge, Louisa Degenhardt, Oye Gureje, Josep Maria Haro, Meredith G. Harris, Aimee Karam, Elie G. Karam, Viviane Kovess-Masfety, Sing Lee, Maria Elena Medina-Mora, Jacek Moskalewicz, Fernando Navarro-Mateu, Daisuke Nishi, José Posada-Villa, Kate M. Scott, Maria Carmen Viana, Daniel V. Vigo, Miguel Xavier, Zahari Zarkov, Ronald C. Kessler, on behalf of the WHO World Mental Health Survey collaborators