1. Boost-glide vehicles for long range transport;Ashford;J. R. Ae. Soc.,1965
2. Proceedings of SAE Space Technology Conference, Palo Alto, California;Tolle,1967
3. Bristol Spaceplanes Limited Report TR 6, February 1994. Carried Out under European Space Agency Contract No. 10411/93/F/TB. Volume 1 Reproduced as ‘The Potential of Spaceplanes’ in the Journal of Practical Applications in Space,1995
4. Civil Aviation Authority,2014
5. ‘The aviation approach to space transportation’;Ashford;Aeronautical Journal of the RAeSoc,2009