@article{zhang2013hyperspectral,
  title={Hyperspectral and panchromatic image fusion using unmixing-based constrained nonnegative matrix factorization},
  author={Zhang, Zhou and Shi, Zhenwei and An, Zhenyu},
  journal={Optik},
  volume={124},
  number={13},
  pages={1601--1608},
  year={2013},
  publisher={Elsevier}
}