Template:Heap-Pregroup
Heap, Christine; Riemsdijk, John van; Science Museum (1985). The pre-grouping railways : their development, and individual characters. London: Her Majesty's Stationery Office. ISBN 0-1129-0432-7. OCLC 19513618.
Heap, Christine; Riemsdijk, John van; Science Museum (1985). The pre-grouping railways : their development, and individual characters. London: Her Majesty's Stationery Office. ISBN 0-1129-0432-7. OCLC 19513618.