Jun-Wen Tan, Adriano O. Andrade, Steffen Walter, Hang Li, David Hrabal, Stefanie Rukavina, Kerstin Limbrecht-Ecklundt, Harald C. Traue: On the use of instantaneous mean frequency estimated from the Hilbert spectrum of facial electromyography for differentiating core affects. BMEI 2012: 568-572