@article {aksen2013bilevel,
	title = {A bilevel p-median model for the planning and protection of critical facilities},
	journal = {Journal of Heuristics},
	volume = {19},
	number = {2},
	year = {2013},
	pages = {373{\textendash}398},
	publisher = {Springer US},
	author = {Aksen, Deniz and Necati Aras and Piyade, Nuray}
}
