In this paper we have proved that union of three grid graphs, U3l=1(Pnl×Pml)and union of finite copies of a grid graph (Pn×Pm)are graceful. We have also given two graceful labeling functions to the grid graph (Pn×Pm).
Bulletin of Mathematical Sciences and Applications (Volume 11)
V.J. Kaneria et al., "Graceful Labeling for Disconnected Grid Related Graphs", Bulletin of Mathematical Sciences and Applications, Vol. 11, pp. 6-11, 2015