J.A. Ripmeester, "Forty-Plus Years of Research in Solid-State NMR Spectroscopy", Encyclopedia of Magnetic Resonance (2010). http://dx.doi.org/10.1002/9780470034590.emrhp1041
R.M. Henkelman, "MRI: A Quantitative Measurement?", Encyclopedia of Magnetic Resonance (2010). http://dx.doi.org/10.1002/9780470034590.emrhp1024