"The notable exception is Durham Cathedral, the nave and choir of which (c. 1104) are supported by the first known examples of pointed ribbed vaults." Norman style at the Encyclopædia Britannica
Warren, John (1991). "Creswell's Use of the Theory of Dating by the Acuteness of the Pointed Arches in Early Muslim Architecture". Muqarnas. 8. BRILL: 59–65, 61–63. doi:10.2307/1523154. JSTOR1523154.
Warren, John (1991). "Creswell's Use of the Theory of Dating by the Acuteness of the Pointed Arches in Early Muslim Architecture". Muqarnas. 8. BRILL: 59–65, 61–63. doi:10.2307/1523154. JSTOR1523154.