Italian Paintings of the Thirteenth and Fourteenth Centuries: Madonna and Child on a Curved Throne, c. 1260/1280 | National Gallery of Art https://www.nga.gov/research/publications/italian-paintings-thirteenth-and-fourteenth-centuries-0/italian-paintings-thirteenth-and-fourteenth-centuries-madonna-and-child-curved-throne-c-12601280
1990; Hoenigswald 1982; Folda 1987, 1995, 1997, 2002, 2005; Polzer 1999, 2002; and Kirsch