1. Principles of Nuclear Magnetic Resonance in One and Two Dimensions;Ernst,1987
2. Spin Dynamics: Basics of Nuclear Magnetic Resonance;Levitt,2001
3. Understanding NMR Spectroscopy;Keeler,2005
4. The normal constants of motion in quantum mechanics treated by projection technique;Löwdin;Rev. Mod. Phys.,1962
5. Application of Löwdin projectors to evaluate density matrix evolutions;Chandrakumar;J. Magn. Reson.,1990