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67Glasersfeld E. von (1981) The concepts of adaptation and viability in a constructivist theory of knowledge [pdf]. In: Sigel I. E., Brodzinsky D. M. & Golinkoff R. M. (eds.) Piagetian theory and research. Hillsdale N. J.: Erlbaum, 87–95. Available at http://www.vonglasersfeld.com/067
67.1German translation: Chapter 13 in 108 (1987).