R Ponraj, SS Narayanan - Internat. J. Math. Combin, 2013 - books.google.com
Let G be a (p, q) graph. Let f: V (G)→{1, 2..., p} be a function. For each edge uv, assign the
label| f (u)− f (v)|. f is called a difference cordial labeling if f is a one to one map and| ef (0) …