Samar Sen-Sarma, Saptarshi Naskar, Krishnendu Basuli, Raju Halder. Research Note The Obscure History of Graph. The Icfai University Journal of Computer Sciences, III(2), April 2009. [doi]
Graph theory has its origin at a definite time and place, which is very unlike the other areas in mathematics - the Königsberg bridge problem, solved in 1736 by Leonhard Euler (Ralf, 1993), and Euler’s theorem for planar graphs, presented in 1752. These results were originally presented in terms of Polyhedra (Ralf).