the Gottschaldt source is:
Kurt GOTTSCHALDT: Der Aufbau des kindlichen Handelns - Vergleichende Untersuchungen an gesunden und psychisch abnormen Kindern. Leipzig: Barth (1933).
I am afraid it was never published in English. Kurt Gottschaldt was an honorary member of the GTA (see http://rdz.acor.org/gestalt!/gerhards/honour.html ). He was one of the most eminent figures of the second generation in Gestalt psychology in Germany. If you are interested to learn more about him and his work you could find some in Mitchell G. ASHs book: Gestalt Psychology in German Culture 1890-1967 - Holism and the Quest for Objectivity (Cambridge: University Press, 1995).