butt mitres

Source reference: 

Clarkson, English Monastic... (1993)

Christopther Clarkson (1993), “English Monastic Bookbinding in the Twelfth Century”, in Ancient and Medieval Book Materials and Techniques: Erice, 18-25 September 1992, edited by Marilena Maniaci and Paola F. Munafò, vol. II, Studi E Testi 358, Città del Vaticano, Biblioteca Apostolica Vaticana, pp. 181–200.

Additional reference: 
p. 195

Used as preferred label for