@ARTICLE{JVLC13, 
	author = {Giuseppe Della Penna and  Daniele Magazzeni and  Sergio Orefice},
	title = {A general theory of spatial relations to support a graphical tool for visual information extraction}, 
	doi = {10.1016/j.jvlc.2012.11.002},
	journal = {Journal of Visual Languages and Computing},
	editor = {Elsevier},

	pages = {71--87},
	year = {2013},
	month = {4},
	volume = {24},
	number = {2}
	
}