EEG Coherency I: Statistics, Reference Electrode, Volume Conduction, Laplacians, Cortical Imaging, and Interpretation at Multiple Scales - Nunez, PL; Srinivasan, R; Wijesinghe, RS; Westdorp, AF; Tucker, DM; Silberstein, RB; Cadusch, PJ (Electro-enceph Clin Neurophysiol, 1997)