ABSTRACT

Springer, Berlin 1983, p. 33. 5. H. Weyl, Philosophy o f Mathematics and Natural Science, Princeton

University Press, Princeton, New Jersey 1949, p. 26. 6 . G. Chartrand (ed.), J. Graph Theory (Special Issue) 10(3), (1986). 7. L. Euler, Conunent. Acad. Scient. Imper. Petropolitanae 8 (1736),

128. 8 . G.R. Kirchhoff, Ann. Phys. Chem. 72 (1847), 497. 9. A. Cayley, Kept. Brit. Assoc. Adv. Sci. 257 (1875).