Sum and integral sum graphs -- A survey

Frank Harary introduced the concepts of sum and integral sum graphs. A graph G is a sum graph if the vertices of G can be labeled with distinct positive integers so that $e = uv$ is an edge of G if and only if the sum of the labels on vertices u and v is also a label in $G.$ An integral sum graph is also defined just as sum graph, the difference being that the labels may be any distinct integers. In this survey article, the authors bring out several properties of sum and integral sum graphs obtained by different authors.