@conference {14549,
	title = {Combination can be hard: Approximability of the unique coverage problem},
	booktitle = {Proceedings of the seventeenth annual ACM-SIAM symposium on Discrete algorithm},
	year = {2006},
	month = {2006///},
	pages = {162 - 171},
	author = {Demaine,E. D and Hajiaghayi, Mohammad T. and Feige,U. and Salavatipour,M. R}
}
