1. Gehrke, C. W., D. Roach, R. W. Zumwalt, D. L. Stalling and L. L. Wall 1968. Quantitative gas-liquid chromatography of amino acids in proteins and biological substances. Analytical Biochemistry Laboratories, Inc., Columbia, Missouri.
2. Mulder, E. G. and K. Bakema. 1956. Effect of the nitrogen, phosphorus, potassium and magnesium nutrition of potato plants on the content of the free amino acids and on the amino acid composition of the protein of the tubers. Plant and Soil 7: 135–166.
3. Ogato, S. and Y. Ishizuka. 1967. Variation of nutritional and physical characteristics of crops by crossing. I. Response of cultivated, wild, and hybrid potatoes to nitrogen. Nippon Dojo-Hiryogaku Zasshi 38: 79–84. (C.A. 67:32032 m).
4. Roach, D., C. W. Gehrke and R. W. Zumwalt. 1969. Quantitative gas-liquid chromatography of histidine. J. Chromatog. 43: 311–321.
5. Roy Choudhury, R. N., A. A. Joseph, K. Indirama, M. Narayana Rao, M. Swaminathan, A. Sreenivasan and V. Subrahmanyan. 1963. Amino acid composition and nutritive value of the proteins of different varieties of potato. Food Science (New Delhi) 12: 255–257.