Erwin Panofsky, Abbot Suger ( Princeton, 1946), 144. The Ordinatio of 1140 or 1141 already contains a few notes about the building of St Denis.
T. Asby, "'The Classical Topography of the Roman Campagna'", in Papers of the British School of Rome, IV ( 1907), 97. Here the whole group of ruins is illustrated. See especially the chamber 'ee' in the plan on plate VIII. Cf. also G. T. Rivoira, Architettura romana ( Milan, 1921), 178.
John Bilson, "'The Beginnings of Gothic Architecture, etc.'", Journal of the Royal Institute of British Architects ( 1899, 1902); "'Durham Cathedral, The Chronology of its Vaults'", in The Archaeological Journal, LXXIX ( 1922), 101.
Sigurd Curman and Johnny Roosval, Sveriges Kyrkor, II, Gotland ( Stockholm, 1935), 95 (illustration) and 114.
Auguste Choisy, L'art de bâtir chez les Romains ( Paris, 1873), 73-5.
The first man to recognize this was probably James Essex ( 1723-84), whose notes are preserved in the British Museum in London. The first man to publish this observation in print was George Saunders in "'Observations on the Origin of Gothic Architecture'" (a lecture read in 1811), in Archaeologia, XVII ( 1814), 15.
The Romanesque crypt of Canterbury Cathedral contains many groin-vaults with double- curved and irregular groins.
Victor Mortet, "'L'expertise de la cathédrale de Chartres en 1316'", C.A., LXVII ( 1901), 323; Frankl, The Gothic, 57 ff.
George Saunders, loc. cit. (Note 12, above.)
Illustrations of these vaults and many others can be found in Marcel Aubert, Croisées d'ogives, extrait, 19, 41, 45, etc.
John Bilson, loc. cit. (Note 7 to Introduction.)
Ernst Gall, "'Neue Beiträge zur Geschichte vom Werden der Gotik'", in Monatshefte für Kunstwissenschaft, IV ( 1911), 309.