Bell, S.M., & Ainsworth, M.D.S. (1972). Infant crying and maternal responsiveness. Child Development, 43, 1171-1190.

Ainsworth, M.D.S., Bell, S.M., Blehar, M.C., & Main, M. (1971). Physical contact: A study of infant responsiveness and its relation to maternal handling. Paper presented at the biennial meeting of the Society for Research in Child Development, Minneapolis, MN.

Ainsworth, M.D.S., Bell, S.M., & Stayton, D.J. (1971). Individual differences in the strange situation behaviour of one-year-olds. In H.R. Schaffer (Ed.), The origins of human social relations. pp. 15-71. New York: Academic Press.

Ainsworth, M.D.S., & Bell, S.M. (1970). Attachment, Exploration, and Separation: Illustrated by the Behaviour of One-Year-Olds in a Strange Situation. Child Development, 41, 49-67.