@article{an2014hyperspectral,
  title={Hyperspectral image fusion by multiplication of spectral constraint and NMF},
  author={An, Zhenyu and Shi, Zhenwei},
  journal={Optik},
  volume={125},
  number={13},
  pages={3150--3158},
  year={2014},
  publisher={Elsevier}
}