Kleiza, V., and J. Verkelis. “Regularities of Signal and Sensitivity Variation of a Reflection Fiber Optopair Sensor Dependent on the Angle Between Axes of Fiber Tips”. Nonlinear Analysis: Modelling and Control, vol. 14, no. 1, Jan. 2009, pp. 41-49, https://doi.org/10.15388/NA.2009.14.1.14529.