APA Style

Ireland, O, S, O. (19--?]). Indexes to the 1/2500 and 6-inch scale maps and small specimens of different maps published . Dublin: [Dublin?.

MLA Style

Ireland, Ordnance, Survey, Of. "Indexes to the 1/2500 and 6-inch scale maps and small specimens of different maps published". Dublin: [Dublin?, 19--?]. Text.