@article {GillisVavasis2,
	title = {Semidefinite Programming Based Preconditioning for More Robust Near-Separable Nonnegative Matrix Factorization},
	journal = {SIAM J. Optim.},
	volume = {25},
	number = {1},
	year = {2015},
	note = {Arxiv link: },
	pages = {677-698},
	author = {Nicolas Gillis and Stephen A. Vavasis}
}