Norden E. Huang, Zheng Shen, Steven R. Long, Manli C. Wu, Hsing H. Shih, Quanan Zheng, Nai-Chyuan Yen, Chi Chao Tung, Henry H. Liu,
The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis Proceedings of The Royal Society A: Mathematical, Physical and Engineering Sciences. ,vol. 454, pp. 903- 995 ,(1998) ,
10.1098/RSPA.1998.0193