1. A. I. Petrenko, A. Ya. Tetel'baum, and B. L. Shramchenko, Computer-Aided Design of Electronic Equipment (A Topological Approach) [in Russian], Vishcha Shkola, Kiev (1980).
2. W. M. Van Cleemput, ?Mathematical models for the circuit layout problem,? IEEE Trans.CAS-23, No. 12, 759?767 (1976).
3. F. Rubin, ?An improved algorithm for testing the planarity of a graph,? IEEE Trans.,C-24, No. 2, 113?121 (1975).
4. A. Kaufmann, An Introduction to Applied Combinatorics [Russian translation], Nauka, Moscow (1975).
5. G. Demoucron, Y. Malgrange, and R. Pertuiset, ?Graphes planaires: reconnaissance et construction des representations planaires topologiques,? Rev. Fr. Rec. Oper.,8, 33?47 (1964).