@article{guide,
author={J. Xu and L. Zhang and D. Zhang}, 
journal={IEEE Transactions on Image Processing}, 
title={External Prior Guided Internal Prior Learning for Real-World Noisy Image Denoising}, 
year={2018}, 
volume={27}, 
number={6}, 
pages={2996--3010}, 
doi={10.1109/TIP.2018.2811546}, 
}