@article{pang20122d,
  title={2D-SPP: a two-dimensional extension of sparsity preserving projections},
  author={Pang, Erping and Wang, Sujing and Qu, Mingzhi and Liu, Rui and Jia, CC and Yu, Zhezhou},
  journal={Journal of Information and Computational Science},
  volume={9},
  number={13},
  pages={3683--3692},
  year={2012}
}