- Stall sound source: from a Youtube video entitled "Stalling and spinning with a Cessna 152" by Morsule. License: CC-BY. Link: https://www.youtube.com/watch?v=zTq8Jvoks2U - Parking brake sound source: from a sound file entitled "Old Lever Pull" by DrMinky. License: kindly allowed it to be used under under the CC0 license. Link: http://freesound.org/people/DrMinky/sounds/167048/ - Trim wheel sound source: from a sound file entitled "rubber.wav" by datasoundsample. License: kindly allowed it to be used under under the CC0 license. Link: http://freesound.org/people/datasoundsample/sounds/41631/