1. Isham, L. B., Moore, Hilary B., and Walton Smith, F. G., “Bulletin of Marine Science of the Gulf and Caribbean”, 1, No. 2, 136 (1951).
2. Attwood, W. D., and Johnson, A. A., “Marine Structures: their Deterioration and Preservation”, Fig. 13, p. 28 (National Research Council, Washington, D.C., 1924).