1. Acidic deposition and sustainable forest management in the central Appalachians, USA
2. Barnes C.P. 1938. The problem: land unit for farming in the humid areas. United States Department of Agriculture Yearbook of Agriculture, pp. 60–67.
3. Gee G.W. and Bauder J.W. 1986. Particle-size analysis. In: Klute A. (ed.), Methods of soil analysis. 2nd ed., Agronomy Monograph Number 9 Part 1 ASA and SSSA Madison, WI, USA, pp. 399–403.