1. C.A. AKesson, 1972 . Studies in ratio estimation . Ph.D. thesis . Psychological Labs., Univ. of Stockholm, Sweden.
2. ASTM. 1968 . Correlation of subjective-objective methods in the study of odors and taste . ASTM Special Technical Publication No. 440.
3. ASTM. 1969 . Reviews of correlations of objective-subjective methods in the study of odors and taste. ASTM Special Technical Publication No. 451.
4. Foundations of multidimensional scaling.