@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} }