Norvig, Gerda S. Dark Figures in the Desired Country. BLAKE'S Illustrations to the Pilgrim's Progress. 375 pp. with 28 color plates and 129 b&w illustrations. 4to, cloth. Berkeley, University of California Press, 1993.
The first detailed study of these rarely seen and powerful watercolors, showing the peak of Blake's draughtsmanship and radically reinterpreting one of the central texts of English literature.