1] R. Alexander, On certain valuations of the vertices of a graph, theory of graphs (internat. symposium, rome, july 1966), Gordon and Breach, NY and Dunod Paris, 1967.
[3] Gary Chartrand, Linda Lesniak, and Ping Zhang, Graphs & Digraphs, vol. 39, CRC press, 2010.
[5] S.M. Hegde, Additively graceful graphs, Nat. Acad. Sci. Lett 12 (1989), 387–390.