Levitt, Malcolm H. 2008. Spin Dynamics: Basics of Nuclear Magnetic Resonance. 2nd ed. Chichester, England: John Wiley & Sons.
Weil, John A. and Bolton, James R. 2007. Electron Paramagnetic Resonance: Elementary Theory and Practical Applications. 2nd ed. Hoboken, N.J.: Wiley-Interscience.