Hegde, S.M.Kumudakshi, K.2026-02-052016Electronic Notes in Discrete Mathematics, 2016, 53, , pp. 149-15415710653https://doi.org/10.1016/j.endm.2016.05.013https://idr.nitk.ac.in/handle/123456789/25924In this paper we present the gracefulness of the directed graph P<inf>m</inf>?P<inf>n</inf>? which is an orientation of the planar grid graph P<inf>m</inf>?P<inf>n</inf>, in which each cell is a unicycle of length four. © 2016 Elsevier B.V.Graceful digraphGrid graph