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3. The development of the senses in the childhood;Shinn M;Univ Cal Public Educ,1904
4. Beiträge zur Kenntnis derphysischen und psychischen Natur des sechsjährigen in die Schule eintretenden Kindes;Engelsberger A;Exp Pat,1905
5. The perspective problem in the aesthetic appreciation of single colors;Bullough E;Br J Psychol,1906