Дробышев, А., Д. Соколов, Aбдуллaевa Ф., Кaнтaевa М., and Дуйсебaев Т. “The Refractive Indices of Thin Films of Vacuum Condensates Cryo Methane”. Recent Contributions to Physics, vol. 2016, no. 3, Sept. 2016, pp. 34-40, https://bph.kaznu.kz/index.php/zhuzhu/article/view/472.