
Source: Quote of Mondrian about his 1890' years; in 'Mondrian, Essays' ('Plastic art and pure plastic art', 1937 and his other essays, (1941-1943) by Piet Mondrian; Wittenborn-Schultz Inc., New York, 1945, p. 10; as cited in De Stijl 1917-1931 - The Dutch Contribution to Modern Art, by H.L.C. Jaffé http://www.dbnl.org/tekst/jaff001stij01_01/jaff001stij01_01.pdf; J.M. Meulenhoff, Amsterdam 1956, p. 40