Gerda S. Norvig, William Blake (1993). “Dark Figures in the Desired Country: Blake's Illustrations to The Pilgrim's Progress”, p.45, Univ of California Press
William Blake (1926). “Preface. General introduction index of symbols. Appendices: The book of Thel. Tiriel. Notes to Reynolds's Discourses. Descriptive catalogue of pictures. 1809. Prose from the Rossetti ms. Table of substituted capitals. Index to foot-notes, &c”, Oxford University Press