History of the Holy See (Vatican City State)
- Provides a history of the Vatican from the time of the Papal States to the present.
- http://www.historyofnations.net/europe/theholysee.html

History of Vatican City: Primary Documents
- Online library and e-text archive of primary source material covering the Catholic Church and the Vatican. Includes transcriptions and translations of early church documents.
- http://library.byu.edu/~rdh/eurodocs/vatican.html

The Holy See Background Note 6/98
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- http://www.state.gov/www/background_notes/holy_see_9807_bgn.html