1. Quantum Mechanics, (Oxford University Press, Oxford, 1935).
2. Determinants and Matrices, (Interscience Publishers, New York, 1956), p. 78.
3. Quantum Theory of Many-Particle Systems. I. Physical Interpretations by Means of Density Matrices, Natural Spin-Orbitals, and Convergence Problems in the Method of Configurational Interaction
4. Computational Methods of Linear Algebra, (Dover Publications, New York, 1959), p. 20.
5. (a) Introduction to Numerical Analysis, (Addison-Wesley Publishing Co., Reading Mass., 1965), p. 96