See pages 3-4 and the section titled 'Forward/Inverse and Scaling Schedule' of DS260 (March 1, 2011 version)
"A full explanation of scaling strategies and their implications is beyond the scope of this document; for more information about this topic; see [Ref 1] and [Ref 2]."
"1. W. R. Knight and R. Kaiser, A Simple Fixed-Point Error Bound for the Fast Fourier Transform, IEEE Trans. Acoustics, Speech and Signal Proc., Vol. 27, No. 6, pp. 615-620, December 1979. 2. L. R. Rabiner and B. Gold, Theory and Application of Digital Signal Processing, Prentice-Hall Inc., Englewood Cliffs, New Jersey, 1975."
A search on the forums will also be helpful. For example: