Второе письмо Уилера Эверетту от 22 мая 1956 г. Box 4, Folder 3, Correspondence from Wheeler to Everett and Others, Oct 1955–Dec 1957, Hugh Everett addition to papers, 1935–1991, American Institute of Physics, Niels Bohr Library & Archives, College Park, MD, USA, http://ucispace.lib.uci.edu/handle/10575/14608.
