Iglesia Católica & Juan XXI, P. (1999). Iohannes XXI, 1276-1277. [Archivio Segreto Vaticano].
Chicago Style (17th ed.) CitationIglesia Católica and Papa Juan XXI. Iohannes XXI, 1276-1277. [Cittá del Vaticano]: [Archivio Segreto Vaticano], 1999.
MLA (9th ed.) CitationIglesia Católica and Papa Juan XXI. Iohannes XXI, 1276-1277. [Archivio Segreto Vaticano], 1999.
Warning: These citations may not always be 100% accurate.