In that dawn : the thirteenth-century in Italy /
Nolthenius, Heĺeǹe.
London : Darton, Longman & Todd,
1968.
A translation of the German 'Duecento', Wertbund-Verlag, 1957.
Originally published as 'Duecento' : Utrecht :  Het Spectrum : 1956.
Includes bibliography (p. 253-262) and index.