@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}
}
@article {aksen2010budget,
	title = {The budget constrained r-interdiction median problem with capacity expansion},
	journal = {Central European Journal of Operations Research},
	volume = {18},
	number = {3},
	year = {2010},
	pages = {269{\textendash}291},
	publisher = {Springer-Verlag},
	author = {Aksen, Deniz and Piyade, Nuray and Necati Aras}
}
