Edmund W. Lowe published two books, the one mentioned previously and "What You Want to Know About Developers", Camera Craft
(San Francisco:1939). Both books went through several editions. Of the two, I think the "What You Want to Know About Developers" is more valuable. While they are small books, 5"x7" and approxiately 120 pages, they are filled with formulas. Either or both would be good additions to any photo library. Search the used book dealers on the net they shouldn't be hard to find. Also recommended, Morris Germain, ARPS, "Darkroom Handbook and Formulary, Ziff-Davis (Chicago:1940).