International
Tables for Crystallography Volume C Mathematical, physical and chemical tables Edited by E. Prince © International Union of Crystallography 2006 
International Tables for Crystallography (2006). Vol. C, ch. 5.2, p. 497

Notation: A and B are the angular apertures (possibly equal) of the two sets of Soller slits; E is the energy of the detected photon; f (E) is the variation of a response (energy of the continuous radiation, absorption in the specimen etc.) with E; g(θ) is an angledependent response (Lorentz factor etc.); I(E −E_{1}) dE is the counting rate recorded at E when the energy of the incident photons is actually E_{1}; R is the diffractometer radius; V is the variance and μ_{3} is the third central moment of the energyresolution function I; 2X, 2Y, 2Z are the effective dimensions (possibly equal) of the source, specimen, and detector; the primes indicate differentiation; the averages <(Δθ)^{2}> etc. are over the range of Bragg angles permitted by the slits etc.
