References
Jan Boom
(1997)., Cognitive development, in W. Van Haaften, M. Korthals & T. Wren (eds.), Philosophy of development, Dordrecht, Springer, pp. 101-117.
(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, Dordrecht, Springer, pp. 221-227.