@inbook {el2012directional,
	title = {Directional Skyline Queries},
	booktitle = {Data and Knowledge Engineering},
	year = {2012},
	note = {n/a},
	pages = {15{\textendash}28},
	publisher = {Springer},
	organization = {Springer},
	abstract = {n/a},
	author = {El-Dawy, Eman and Hoda M. O. Mokhtar and Ali El-Bastawissy}
}
