1. Bronfenbrenner, U. (1992). Ecological systems theory. In R. Vasta (Ed.), Six theories of child development: Revised formulations and current issues (pp. 187-248). Philadelphia: Jessica Kingsley.
2. Dunst, C.J. (1996). Early intervention in the USA: Programs, models, and practices. In M. Brambring, H. Rauh, & A. Beelmann (Eds.), Early childhood intervention: Theory, evaluation, and practice (pp. 11-52). Berlin, Germany: Walter de Gruyter.