Effectiveness and Cost-Effectiveness of a Self-Guided Internet Intervention for Social Anxiety Symptoms in a General Population Sample: Randomized Controlled Trial oleh Powell, John, Williams, Veronika, Atherton, Helen, Bennett, Kylie, Yang, Yaling, Davoudianfar, Mina, Hellsing, Annika, Martin, Angela, Mollison, Jill, Shanyinde, Milensu, Yu, Ly-Mee, Griffiths, Kathleen M