1. Bushnell, John. The effect of soil reaction on the fertilizer requirements of the potato. Proc. Potato Assoc. Amer. 13: 12–14. 1926.
2. Bushnell, John. Liming potato soils. Ohio Agr. Exp. Sta. Spec. Circ. 30, p. 38. 1930.
3. Wessels, P. H. Soil acidity studies with potatoes, cauliflower, and other vegetables on Long Island. Cornell Univ. Agr. Expt. Sta. Bul. 536. 1932.