An injection from the vertices of a graph G to the group of integers modulo k, where k is the number of edges of G, generates a bijection between the edges of G and the numbers modulo k by taking the edge label for an edge ab to be the sum of the labels of the two vertices ab (modk). We show in this work that symmetrical trees with a diameter of four allow for harmonic labelling. Error-correcting codes and channel assignment difficulties can both benefit from the usage of harmonious graphs.**Author (S) DetailsAmaresh Chandra Panda**Department of Mathematics, C.V. Raman College of Engineering, Bhubaneswar, 752054 Odisha, India.

**Former ProfessorDebdas Mishra**

Department of Mathematics, C.V. Raman College of Engineering, Bhubaneswar, 752054 Odisha, India.

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