Xin, Z., S. Jie, A. Wenwei, Y. Tiantian, and R. Malekian. “An Improved Time-Frequency Representation Based on Nonlinear Mode Decomposition and Adaptive Optimal Kernel”. Elektronika Ir Elektrotechnika, vol. 22, no. 4, Aug. 2016, pp. 52 -57, doi:10.5755/j01.eie.22.4.15918.