Sede Vacante 1241
August 22, 1241—October 25, 1241
November 10, 1241—June 24, 1243
Documents concerning the Elections of 1241 and 1241-1243
- Emperor Frederick states the purpose of his operations in Tuscany (February. 1240)
- Bartholomaeus, scriba of Genoa, Annales, concerning the capture of the cardinals (May 3, 1241).
- Matthew of Paris, Chronica majora . selections related to the Elections of 1241 and 1241-1243
- Flores Historiarum, under the pseudonym 'Matthew of Westminster'
- Ryccardus de San Germano, sub annis 1241, 1242, 1243 [MGH SS 19, 380-384]
- Letter of the Emperor Frederick II to Cardinal Colonna (1241)
- Letter of the Emperor Frederick, about his military successes in Spring, 1241
- Letter of seven Archbishops and Bishops to Pope Gregory, about their escape from the Battle (May 3, 1241).
- Letter of Gregory IX to Genoa, counselling revenge (August 16, 1241).
- "Letter" of an anonymous cardinal to Chancellor Pietro de Vigna (1241).
- Hampe's Anonymous, letter of cardinals at Anagni to the cardinals in Rome (November, 1241).
- Letters of the Emperor Frederick II to the College of Cardinals during the second Election (Spring 1242)
- Letter of Matteo Rosso Orsini to the leaders of Alatri, summoning them to war against the Imperial Forces (June 14, 1242).
- Cardinal Raynerius of S. Maria in Cosmedin and the taking of Viterbo (1243).