Jiri Smejcky and Vitezslav Jerabek (2020) “Differential Gain Comparison of Optical Planar Amplifier on Silica Glasses Doped with Bi-Ge and Er, Yb Ions”, Journal of Material Science and Technology Research, 7, pp.  71–79. doi: 10.31875/2410-4701.2020.07.08.