@inbook {DBLP:reference/gis/Skiadopoulos17,
	title = {Directional Relations},
	booktitle = {Encyclopedia of GIS.},
	year = {2017},
	pages = {476{\textendash}482},
	doi = {10.1007/978-3-319-17885-1_1539},
	url = {https://doi.org/10.1007/978-3-319-17885-1_1539},
	author = {Spiros Skiadopoulos}
}
