Ainsworth, M. D. S. / 1979 / Attachment as related to mother-infant interaction, In Advances in the study of behavior, 9 / Academic Press : 1 ~ 51 Cassidy, J. / 1988 / Avoidance and its relation to other defensive processes, In Clinical implications of attachment / Erlbaum : 300 ~ 317 Cohen, S. / 1985 / Stress, social support and the buffering hypothesis / Psychological Bulletin 98 (2) : 310 ~ 357 Creswell, J. W. / 2003 / Research design: Qualitative, quantitative, and mixed methods approaches / Sage Docherty, S. / 1999 / Focus on qualitative methods : Interviewing children / Research in Nursing and Health 22 (2) : 177 ~ 185