F. A. M. Frescura, B. J. Hiley: Algebras, quantum theory and pre-space, pp. 3–4 (published in Revista Brasileira de Fisica, Volume Especial, Julho 1984, Os 70 anos de Mario Schonberg, pp. 49–86)
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David Bohm: Time, the implicate order, and pre-space, In: David R. Griffin: Physics and the Ultimate Significance of Time, State University of New York Press, 1986, ISBN 0-88706-113-3, pp. 177–208, p. 183
David Bohm: Time, the implicate order, and pre-space, In: David R. Griffin: Physics and the Ultimate Significance of Time, State University of New York Press, 1986, ISBN 0-88706-113-3, pp. 177–208, pp. 192–193