1. C. Berge, “Theorie des Graphes et Ses Applications,” ( Dunod, Paris, 1958 ) pp. 31–32.
2. R. J. Preiss, “Design Automation Survey,’ IBM Technical Note, TN 00.480 (1960) pp. 3–4.
3. U. R. Kodres, ‘Geometrical Positioning of Circuit Elements in a Computer, AIEE CP 59–1172 (Oct., 1959 ).
4. J. B. Kruskal, Jr., On The Shortest Spanning Subtree of a Graph and the Traveling Salesman Problem, Proc. Am. Math. Soc., Vol. 7 (1956) pp. 48–50.
5. R. E. Gomory, “An Algorithm for Integer Solutions to Linear Programs,’ Princeton—IBM Mathematics Research Project Technical Report, No. 1 (Nov. 17, 1958 ).