DST, R.; SO, S. Skolem Mean Labeling of Four Star Graphs K_(1,a_1 )∪ K_(1,a_2 )∪ K_(1,a_3 )∪ K_(1,b) where |b - (a_1+a_2+a_3)| = 4. Journal of Computational Mathematica, v. 2, n. 1, p. 75-79, 30 Jun. 2018.