Parkinson, R.C. (December 1991). The An-225/Interim Hotol Launch Vehicle. 3rd International Aerospace Planes Conference. Orlando, Florida. doi:10.2514/6.1991-5006.
espacenet.com
worldwide.espacenet.com
GB patent 2241537, John Scott-Scott; Bryan Belcher & Alan Bond, "Prevention of icing in the intakes of aerospace propulsors", published 4 September 1991, issued 12 August 1992, assigned to Rolls-Royce Plc