Fernand Khnopff, Gerard Brown, Léonce Bénédite, Marion H. Spielmann, Richard Muther and John Van Dyke, 1911 Encyclopædia Britannica (1911)
“ The painters of the Sienese school were on the whole faithful to the style indicated, and later on in the century they extend the boundaries of their school by spreading its influence into the hill country of Umbria. In the cities of this region Taddeo di Bartoli, one of the best of the followers of Simone, worked about the end of the century, and early Umbrian art in consequence exhibits the same devotional character, the same dreaminess, the same grace and decorative charm, that are at home in Siena. ”
