Matthias Winterhalder Björn Schelter Jens Timmer Detecting Coupling Directions in Multivariate Oscillatory Systems. 3735-3739 2007 17 Int. J. Bifurc. Chaos 10 https://doi.org/10.1142/S0218127407019664 db/journals/ijbc/ijbc17.html#WinterhalderST07