WilliamsP.C., in Near-Infrared Technology in Agricultural and Food Industries, Ed. by WilliamsP. and NorrisK.Am Assoc. Cereal Chemists, St Paul, Minnesota, USA, p. 113. (1987).
2.
SokolnikoffI.S., Advanced Calculus.McGraw-Hill Book Company, New York, pp. 82ff. (1939).
3.
AbramowitzM. and StegunI.A., (Eds), Handbook of Mathematical Functions. National Bureau of Standards Applied Mathematics Series 55, US Government Printing Office, Washington, DC, USA, p. 877 (1964).