Jonathan de Ferranti. "Helvellyn North". Viewfinder Panoramas. Retrieved 9 August 2014.
Jonathan de Ferranti. "Helvellyn South". Viewfinder Panoramas. Retrieved 9 August 2014.
waymarking.com
flipflopnick (2008). "First Aircraft landing on a mountain in GB". waymarking.com. Retrieved 1 August 2014. which cites the book: Peter Connon (1984). Aeronautical History of the Cumbria, Dumfries and Galloway Region: 1915–30. Penrith, Cumbria: St Patrick's Press. ISBN978-0-9508287-1-8.