@INPROCEEDINGS {4378,
author={J.   Nascimento and J. Bioucas-Dias},
doi={10.1109/IGARSS.2007.4423531 },
booktitle={IEEE International Geoscience and Remote Sensing Symp.- IGARSS},
title={Hyperspectral Signal Subspace Estimation},
year={2007},
month={July},
volume={-},
pages={3225-3228} 
}