Netherlands (Kingdom, 1815- )Bijzondere Commissie voor de Afdeeling der Wetenschappen, Internationale Tentoonstelling te Luik, 1930.; Royal Academy of Science, universities and higher schools in Holland and the Dutch East Indies
The Netherlands Central society for rehabilitation and world Committee on Special Education of the International Society for Rehabilitation of the Disabled; Bakker, P. D.; Moulijn, C. D.; Van den Broek, P.