9Norden E. Huang, Man-li C. Wu, Steven R. Long, etc. A confidence limit for the empirical mode decomposition and Hilbert spectral anal- ysis. The Royal Society. Proc. R. lond. A (2003)459,2317 -2345.
10Huang N E Shen Zheng Long S R et al The empirical mode decom- position and the Hilbert spectrum for nonlinear and nonstationary time series analysis[J] Proc. R. Soc. Lond. 1998 A:903 -995.