Wolfgang Pauli (2008). “Wissenschaftlicher Briefwechsel mit Bohr, Einstein, Heisenberg u.a. Band IV, Teil III: 1955–1956. Scientific Correspondence with Bohr, Einstein, Heisenberg, a.o. Volume IV, Part III: 1955–1956”, p.148, Springer-Verlag
Agnes Martin, Lawrence Alloway, University of Pennsylvania. Institute of Contemporary Art (1973). “Agnes Martin: exhibition January 22 to March 1, 1973”