Dash, Samuel (1976): Chief Counsel: Inside the Ervin Committee – The Untold Story of Watergate, New York: Random House. s. 259–260, ISBN 0-394-40853-5. OCLC [2388043 2388043]. Sitat: «Soon Alexander Haig and James St. Clair learned of the existence of this tape and they were convinced that it would guarantee Nixon's impeachment in the House of Representatives and conviction in the Senate.»
Perry, James M. : «Watergate Case Study», Class Syllabus for ’Critical Issues in Journalism’, Columbia School of Journalism, Columbia University. Arkivert fra originalen den 15. juli 2019.
congress.gov
crsreports.congress.gov
Rybicki, Elizabeth; Greene, Michael (10. oktober 2019): «The Impeachment Process in the House of Representatives», CRS Report for Congress. Washington, D.C.: Congressional Research Service, Library of Congress. s. 5–7. R45769. Arkivert fra originalen den 22. januar 2020.
«The Smoking Gun Tape» (Transcript of the recording of a meeting between President Nixon and H. R. Haldeman). Watergate.info 23. juni 1972. Arkivert fra originalen den 1. mai 2012.
web.archive.org
Perry, James M. : «Watergate Case Study», Class Syllabus for ’Critical Issues in Journalism’, Columbia School of Journalism, Columbia University. Arkivert fra originalen den 15. juli 2019.
Rybicki, Elizabeth; Greene, Michael (10. oktober 2019): «The Impeachment Process in the House of Representatives», CRS Report for Congress. Washington, D.C.: Congressional Research Service, Library of Congress. s. 5–7. R45769. Arkivert fra originalen den 22. januar 2020.
Manheim, Karl; Solum, Lawrence B. (våren 1999): "Nixon Articles of Impeachment", Impeachment Seminar. Arkivert fra [the original originalen] den 3. mars 2017.
«The Smoking Gun Tape» (Transcript of the recording of a meeting between President Nixon and H. R. Haldeman). Watergate.info 23. juni 1972. Arkivert fra originalen den 1. mai 2012.