KamenevО. T., Y. S. Petrov, and A. A. Podlesnykh. “Use of 3×3 Coupler in the Fiber Optic Strainmeter Based on Mach-Zehnder Interferometer”. KnE Energy, Vol. 3, no. 3, Apr. 2018, pp. 388–392, doi:10.18502/ken.v3i3.2052.