found:Catholic Church. Pope (1370-1378 : Gregory XI). Grégoire XI, 1370-1378 : lettres communes analysées ... 1992-
found:New Cath. encyc.(Gregory XI, Pope Dec. 30-1370 to Mar. 27, 1378; b. Pierre Roger de Beaufort, 1329)
found:Encyc. Brit., 15th ed.(Gregory XI, originally Pierre-Roger de Beaufort, b. 1329, d. Mar. 26/27, 1378)
found:Dict. de biogr. franç.(Grégoire XI, pape: Pierre-Roger de Beaufort, b. 1329, d. Mar. 26/27, 1378)