The method of Lanczos for calculating the characteristic roots and vectors of a real symmetric matrix
R. A. Brooker, F. H. Sumner · The proceedings of the Institution of Electrical Engineers. Part B, Radio and electronic engineering, including communication engineering · 1956
The paper draws attention to a method suggested by Lanczos for arriving at the reduced characteristic function of a matrix, and shows how it may be used with an electronic computer to evaluate automatically the characteristic roots and vectors of a real symmetric matrix, no matter how degenerate.