Donalong. (Fort of Cool-more / 
West,.
[Dublin] :  Ordnance Survey Office, 
[1837]
In: Ordnance Survey of the County of Londonderry ... Volume the first. p. 236.
The map of Donalong is from a M.S. in the Library of Trinity College, Dublin, and that of Cool-more from a M.S. by Sir Thomas Phillips about 1625.