Casgliadau Arlein
Amgueddfa Cymru
Chwilio Uwch
Ordnance survey map 1:2,500
OS map: Sirhowy Valley, Hollybush Colliery, Pontgwaith level (coal). Monmouth sheet (photocopy)? 25", 1877. Scale 1/2500 or 25.344 inches to a Statute mile or 208.33 feet to one inch.
Nid yw sylwadau ar gael ar hyn o bryd. Ymddiheuriadau am yr anghyfleustra.