1. J. Douglas, Jr. and D. W. Peaceman, Numerical solution of two-dimensional heat-flow problems, A. I. Ch. E. J. 1, 505-512 (1955)
2. G. H. Bruce, D. W. Peaceman, H. H. Rachford, Jr. and J. D. Rice, Calculation of unsteady-state gas flow through porous media, Trans. Am. Inst. Mining Met. Engrs. 198, 79-92 (1953)
3. R. Bellman, On the weak and strong stability of numerical solutions of partial differential equations. 1. The heat equation, Princeton University Rept. AECU-3275 (1958)
4. G. Birkhoff and S. MacLane, A survey of modern algebra, chap. IX, sec. 9, The Macmillan Co., New York, 1951
5. C. Caratheodory, Conformal representations, chap. V, University Press, Cambridge, 1932