@article{imagepatchanalysisofsunspotsandactive1,
  title = {Image patch analysis of sunspots and active regions. II. Clustering via matrix factorization},
  author = {Kevin R. Moon and Veronique Delouille and Jimmy J. Li and Ruben De Visscher and Fraser Watson and Alfred O. Hero III},
  year = {2015},
  eprint = {1504.02762},
  archivePrefix = {arXiv},
  url = {http://arxiv.org/abs/1504.02762v2},
}