1. E. J. Shellard, “Quantitative Paper and Thin-Layer Chromatography”, Academic Press, New York, N. Y. 1968.
2. T. L. Saaty, “Mathematical Methods of Operations Research”, McGraw-Hill Book Co. Inc. New York 1959, p. 367.
3. E. Stahl, “Thin-Layer Chromatography”, Springer-Verlag, Berlin 1962, p. 100.