Stojce Ilcev, Dimov. “Surveillance Radars Onboard Stratospheric Platform Systems (SPS) for Ship Tracking”. International Journal of Engineering and Technology 7, no. 4 (December 17, 2018): 4191–4194. Accessed February 9, 2026. https://www.sciencepubco.com/index.php/IJET/article/view/21104.