References
Jan Boom
(1997). Cognitive development. In W. Van Haaften, M. Korthals, & T. Wren (Eds.). Philosophy of development (pp. 101-117). Dordrecht: Springer.
(1990). Two conceptions of stage structure and the problem of novelty in development. In M. E. Hyland, W. J. Baker, R. Van Hezewijk, & S. J. S. Terwee (Eds.). Recent trends in theoretical psychology (pp. 221-227). Dordrecht: Springer.