[2] "The formation of NOx", Alentecinc.com., 2010.
books.google.com
E. C. Fernandes and M. V. Heitor, “Unsteady flames and the Rayleigh criterion” in F. Culick, M. V. Heitor, and J. H. Whitelaw: Unsteady Combustion (Dordrecht, the Netherlands: Kluwer Academic Publishers, 1996), p. 4