1. Aviation Accident Reports - National Transportation Safety Board.
http://www.ntsb.gov/investigations/AccidentReports/Pages/aviation.aspx/
. Last visit: 10/04/2015
2. International Helicopter Safety Team.
http://www.ihst.org/
. Last visit: 21/04/2015
3. Quinliven, T.A., Long, K.R.: Rotor performance in the wake of a large structure. In: Proceedings of AHS International 65th Annual Forum, vol 3, pp. 1878–1906 (2009)
4. Polsky, S.A., Wilkinson, C.H.: A computational study of outwash for a helicopter operating near a vertical face with comparison to experimental data. In: AIAA Modeling and Simulation Technologies Conference 10–13 August 2009, Chicago, Illinois, AIAA 2009–5684 (2009). doi:
10.2514/6.2009-5684
5. Gibertini, G., Grassi, D., Parolini, C., Zagaglia, D., Zanotti, A.: Experimental investigation on the aerodynamic interaction between a helicopter and ground obstacles. Proc Inst Mech Eng Part G J Aerospace Eng 229(8):1395–1406 (2015).
http://pig.sagepub.com/content/229/8/1395.full.pdf