– Ferdinand Hurter, Ph.D., and V. C. Driffield, “Photo-chemical Investigations and a new Method of Determination of the Sensitiveness of Photographic Plates” (Reprinted from The Journal of the Society of Chemical Industry, 31st May, 1890, No. 5, Vol. IX)
[“The Photographic Research of Ferdinand Hurter & Vero C. Driffield” (A Facsimile Edition), Morgan & Morgan, Inc., Dobbs Ferry, New York 1974, p. 76]
