1. The Numerical Solution of Parabolic and Elliptic Differential Equations
2. Elliptic Problems in Linear Difference Equations over a Network, Watson Scientific Computing Laboratory;Thomas,1949
3. L.H. Thomas, Elliptic problems in linear equations over a network, Special Collection Dept. of the North Carolina State Univ. Libraries, the Llewellyn Hilleth Thomas Papers 1921–1989, item 210.8–13.8, 1949.
4. Some Design Features of a Sparse Matrix Code
5. http://hsl.rl.ac/archive/hslarchive.html.