8Leask, H.G., Liam Price, C.P. Martin, and K.C. Bailey. "The Labbacallee Megalith, Co. Cork." Proceedings of the Royal Irish Academy. Section C: Archaeology, Celtic Studies, History, Linguistics, Literature 43 (1936): 83.
The authors report on similar Irish tombs with port holes: "The dolmen in Burren Townland, Co. Cavan, has a partition slab between its two chambers with a port-hole in the bottom edge and, in the Deerpark townland dolmen, Co. Clare, the eastern partition stone has two port-holes: one in the side of the stone and the other at one of the upper corners. The Labbacallee port-hole, at the top northern corner of stone 60- if indeed, it be a port-hole at all, which is by no means certain-bears some resemblance to the Deerpark example."