Kien, F. L., T. Busch, V. G. Truong, and S. N. Chormaic. “Chirality of Light in Hybrid Modes of Vacuum-Clad Ultrathin Optical Fibers”. Communications in Physics, vol. 27, no. 1, Mar. 2017, p. 23, doi:10.15625/0868-3166/27/1/9240.