W. Grohmann, Paul Klee, Stuttgart, 1954, p. 284 (illustrated). J. Spiller, Paul Klee. Das bilderische Denken. Formund Gestaltungslehre, Basel, 1956, p. 72. M. Huggler, Paul Klee. Die Malerei als Blick in den Kosmos, Stuttgart, 1969, p. 105. R. Verdi, "Paul Klee's Fish Magic an Interpretation" in The Burlington Magazine, 1974, pp. 147-155. J. Pierce, Paul Klee and Primitive Art, Ph.D. diss., New York, 1976, pp. 150 and 153. D. Chavalier, Paul Klee, Neue Ergänzte Ausgabe, Munich, 1979, p. 47 (illustrated in color). B. Tower, Klee and Kandinsky in Munich and at the Bauhaus, Ann Arbor, 1981, p. 184 (illustrated, p. 140). R. Verdi, Klee and Nature, London, 1984, p. 184 (illustrated). E.G. Guse, Paul Klee Dialogue with Nature, Munich, 1991, p. 27 (illustrated). J. Anger, Modernism and the Gendering of Paul Klee, Ph.D. diss., Providence, 1997, p. 164. The Paul Klee Foundation, ed., Paul Klee: Catalogue Raisonné, Bern, 2001, vol. 5, p. 43, no. 4232 (illustrated; illustrated in color, p. 57).