@article{ontheworstcaseapproximabilityofsparse,
  title = {On the Worst-Case Approximability of Sparse PCA},
  author = {Siu On Chan and Dimitris Papailiopoulos and Aviad Rubinstein},
  year = {2015},
  eprint = {1507.05950},
  archivePrefix = {arXiv},
  url = {http://arxiv.org/abs/1507.05950v1},
}