O'Begly 1732. O'Begly, Conor (1732). An Focloir Bearla Gaoidheilge. Bar na chur acclodh le Seumas Guerin, an bhiadhain dloir an tiaghurna. p. 145 – via books.google.com.
Etymology Online, "shillelagh (n.)": "1772, "cudgel," earlier, "oak wood used to make cudgels" (1670s), from Shillelagh, town and barony in Co. Wicklow, Ireland, famous for its oaks" "Shillelagh". etymonline.com. Online Etymology Dictionary.
Oxford English Dictionary 1989, "shillelagh": "Etymology: [..] the name of a barony and village in Co. Wicklow [..] 1785 F. Grose Classical Dict. Vulgar Tongue, Shillaley, an oaken sapling, or cudgel, (Irish) from wood of that name famous for its oaks" "Shillelagh". Oxford English Dictionary (Second Edition, Volume 15).