Niels Bohr's response to questions on the nature of language during his first meeting with Werner Heisenberg (Summer 1920), as quoted in "Discussions about Language", 1933, in Robert J. Pranger "Defense Implications of International Indeterminacy" (p. 11), 1972, and in Steve Giles "Theorizing Modernism: Essays in Critical Theory" (p. 28), 1993.
"The Philosophical Writings of Niels Bohr, Volume IV: Causality and Complementarity" edited by Jan Faye and Henry J. Folse (1998); later quoted in Karen Michelle Barad "Meeting the Universe Halfway: Quantum Physics and the Entanglement of Matter and Meaning" (p. 254), 2007.