Williamson, Harold Francis, 1901- Designed for digginng; the first 75 years of Bucyrus-Erie Company, by Harold F. Williamson and Keneeth H. Myers, II. Evanston, I11., Northwestern University Press, 1955. 384 p. ilus., retratos. 29 cm. (Northwestern University studies in business history, v.2) Incluye bibliografía