Harrison, Hope. "The Berlin Wall, Ostpolitik and Détente"(PDF). Archived from the original(PDF) on 8 January 2012. (91.1 KB) German historical institute, Washington, DC, Bulletin supplement 1, 2004, American détente and German ostpolitik, 1969–1972".
Harrison, Hope. "The Berlin Wall, Ostpolitik and Détente"(PDF). Archived from the original(PDF) on 8 January 2012. (91.1 KB) German historical institute, Washington, DC, Bulletin supplement 1, 2004, American détente and German ostpolitik, 1969–1972".