1. Levin E. and Zaynal S., “Voice communication system for air traffic control. Development and evaluation of a prototype,” Master of Science Thesis in Software Engineering and Technology, Chalmers University of Technology University of Gothenburg Department of Computer Science and Engineering, Göteborg, Sweden, 2011.
2. R. Cox, S. de Campos Neto, C. Lamblin, and M. Sherif, “ITU-T coders for wideband, superwideband, and fullband speech communication,” IEEE Communications Magazine, Vol. 47, No. 10, pp. 106–109, Oct. 2009, https://doi.org/10.1109/mcom.2009.5273816
3. Preobragenskiy I. N., Stability and Oscilations of Plates and Shells with the Holes. Moscow: Mashinostroenie, 1981.
4. L. V. Kurpa, “Natural vibrations of plates with holes,” Soviet Applied Mechanics, Vol. 15, No. 2, pp. 173–175, Feb. 1979, https://doi.org/10.1007/bf00884587
5. R. F. Hegarty and T. Ariman, “Elasto-dynamic analysis of rectangular plates with circular holes,” International Journal of Solids and Structures, Vol. 11, No. 7-8, pp. 895–906, Jul. 1975, https://doi.org/10.1016/0020-7683(75)90012-8