Hoi, P. V., N. T. Anh, N. T. T. Trang, L. H. Thang, and N. V. An. “Enhancement of Lasing Emission in the Metalliccoated Microsphere Cavity Based on Er-Doped Silica Glasses”. Communications in Physics, vol. 25, no. 3, Dec. 2015, p. 195, doi:10.15625/0868-3166/25/3/6994.