1. Department of Sociology and Social Work, Minzu University of China, No. 27 Zhongguancun S St, Haidian, Beijing 100081, China
2. Department of Social Sciences, University of Eastern Finland; Yliopistonranta 1, P.O. Box 1627, FI-70211 Kuopio, Finland
3. Department of Social Work, Fudan University, No.220 Han Dan Road, Shanghai 200433, China