Source reference:
Middleton (1994, 4th ed.)
Bernard Middleton, A history of English Craft Bookbinding Techniques, New Castle, London, Oak Knoll Press, The British Library, 1994 (4th ed.)
Additional reference:
p. 63
Oxford Companion to the Book (2010)
Michael Felix Suarez and H. R. Woudhuysen, eds (2010), The Oxford Companion to the Book, 2 vols, Oxford, Oxford University Press.