A method of quantitative spectrochemical analysis, first suggested by W. Gerlach and W. Rollwagen and making use of line widths, is described and discussed. The method is practical and accurate; it is independent of development conditions or exposure time and it may be applied to cases where customary techniques fail.
PIERRE COHEUR, "A Method of Quantitative Spectrochemical Analysis Based on Line Widths," J. Opt. Soc. Am. 36, 498-500 (1946)