Pomeroy, L.R., Darley, W.M., Dunn, E.L., Gallagher, J.L., Haines, E.B., Whitney, D.M., 1981.
Snedden, J.W., Kreisa, R.D., Tillman, R.W., Culver, S.J., Schweller, W.J., 1999. An expanded
Thomas, R.G., Smith, D.G., Wood, J.M., Visser, J., Caverley-Range, E.A., Koster, E.H., 1987.