Jones & Bartlett. p. 13. ↑ 51°30′48″N 0°8′12″W﻿ / ﻿51.51333°N 0.13667°W﻿ / 51.51333; -0.13667Coordinates: 51°30′48″N 0°8′12″W﻿ / ﻿51.51333°N 0.13667°W﻿ / 51.51333; -0.13667 ↑ Snow 1855, p. 38. ↑ Snow 1855, p. 45. ↑ Johnson, Steven (2006).