@article{PNMFAFIP,
author = {Zhirong Yang, Zhijian Yuan and Jorma Laaksonen},
journal = {International Journal on Pattern Recognition \& Artificial Intelligence},
number = {8},
pages = {1353-1362},
title = {Projective Nonnegative Matrix Factorization with Applications to Facial Image Processing},
volume = {21},
year = {2007},
}