Janet Zapata, The Jewelry and Enamels of Louis Comfort Tiffany, New York, 1993, pp. 49-52 (for related enameled copper vases). John Loring, Louis Comfort Tiffany at Tiffany & Co., New York, 2002, pp. 100, 115-119 (for related enameled copper vases) and pp. 216-218 (for related glazed earthenware vases). Martin Eidelberg, Alice Cooney Frelinghuysen, Nancy A. McClelland and Lars Rachen, The Lamps of Louis Comfort Tiffany, New York, 2005, p. 57 (for a watercolor study of hollyhocks). Marilynn A. Johnson, Louis Comfort Tiffany: Artist for the Ages, London, 2005, p. 146 (for a related glazed earthenware vase). Martin Eidelberg, Nina Gray and Margaret K. Hofer, A New Light on Tiffany: Clara Driscoll and the Tiffany Girls, London, 2007, p. 95 (for the same watercolor study). Martin Eidelberg, Tiffany Favrile Pottery and the Quest of Beauty, New York, 2010, pp. 20, 29, 31, 34, 39, 53-54 and 93 (for related glazed earthenware vases) and p. 94, no. 220 (for the Hollyhock model in glazed earthenware)