@article {7342,
	title = {Liquid nitrogen energy storage unit},
	journal = {Cryogenics},
	volume = {51},
	year = {2011},
	pages = {621-29 },
	author = {J. Afonso and I. Catarino and R. Patr{\'\i}cio and A. Rocaboy and M. Linder and G. Bonfait}
}
