5Vygotsky, 1978. Mind in Society: The Development of Higher Psychological Processes. Harvard University Press.
6Laura E Berk & Adam Winsler. 1995. Scaffolding Children's Learning. NAEYC.
7Ann L Brown & Roberta A Ferrara.1985. Diagnosing Zones of Proximal Development, in James V Wertsch(Ed.) Culture, Communication, and Cognition. The Press Syndicate of the University of Cambridge.
8Mariana Hedegaard.1990. Zones of Proximal Development as Basis for Instruction. in Luis C Moll (EA) Vygotsky and Educationz Instructional Implications and Applications of Sociohistorical Psychology . The Press Syndicate of the University of Cambridge.
9Seng Seok-Hoon.1997. ZPD and the World of the Child . (abstraction) in ERIC.
