"The New Pressurised Marksman". Air-Britain Heston. Heston and Heathrow Branch of Air-Britain. 24 April 2010. Archived from the original on 23 Jul 2012. Retrieved 27 January 2020.
btinternet.co.uk
abheston.btinternet.co.uk
"The New Pressurised Marksman". Air-Britain Heston. Heston and Heathrow Branch of Air-Britain. 24 April 2010. Archived from the original on 23 Jul 2012. Retrieved 27 January 2020.