1. Ash, Mitchell. (1995) Gestalt Psychology in German Culture 1890–1967: Holism and the Quest for Objectivity. Cambridge, UK: Cambridge University Press, 1995.
2. von Ehrenfels, Christian. (1890) “On ‘Gestalt Qualities.’” Foundations of Gestalt Theory. Barry Smith, ed. and trans. Munich/Vienna: Philosophia Verlag, 1988, pp. 82—117. Originally published as “Über ‘Gestaltqualitäten.’” Vierteljahrschaftliche Philosophie, 14, 1890, pp. 249–92. Trans. Barry Smith.
3. von Ehrenfels, Christian. (1916) “Ground Level and Gestalt Purity.” Foundations of Gestalt Theory. Barry Smith, ed. and trans. Munich/Vienna: Philosophia Verlag, 1988, pp. 118–120. Originally published in Ehrenfels’ Kosmogonie. Jena: Diederichs, 1916, pp. 93–96.
4. von Ehrenfels, Christian. (1937) “On Gestalt Qualities.” Foundations of Gestalt Theory. Barry Smith, ed. Munich/Vienna: Philosophia Verlag, 1988, pp. 121–123. Originally published in Philosophia (Belgrade), 2, 1937, pp. 139–41. Trans. by Mildred Focht for Psychological Review, 44, 1937, pp. 521–24.
5. Ellis, Willis D. (ed.) A Source Book of Gestalt Psychology. London: Routledge & Kegan Paul Ltd., 1938.