1. Bates D. M. and D. G. Watts. 1988. Nonlinear regression analysis and its applications p. 27 144. John Wiley & Sons Inc. New York.
2. Bevington P. 1969. Data reduction and error analysis for the physical sciences p. 182. McGraw-Hill Book Company New York.
3. Gilbert N. 1989. Biometrical interpretation: making sense of statistics in biology 2nd ed. p. 64. Oxford University Press New York.
4. Statistical aspects of the microbiological analysis of foods;Jarvis B.;Prog. Industrial Microbiol.,1989
5. Krieg N. R. (ed.). 1984. Bergey's manual of systematic bacteriology vol. 1 p. 498. The Williams & Wilkins Co. Baltimore.