Warsitz, Ernst, and Reinhold Haeb-Umbach. “Acoustic Filter-and-Sum Beamforming by Adaptive Principal Component Analysis.”https://doi.org/10.1109/ICASSP.2005.1416129__In IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP 2005), 4:iv/797-iv/800 Vol. 4, 2005.https://doi.org/10.1109/ICASSP.2005.1416129 .

Warsitz, Ernst, and Reinhold Haeb-Umbach. “Robust Speaker Direction Estimation with Particle Filtering.”https://doi.org/10.1109/MMSP.2004.1436569__In IEEE Workshop on Multimedia Signal Processing (MMSP 2004), 367–70, 2004.https://doi.org/10.1109/MMSP.2004.1436569 .