@inbook {5,
	title = {The PHOS Language for Conceptual Knowledge Representation},
	booktitle = {Engineering Systems with Intelligence. Concepts, Tools and Applications},
	year = {1992},
	pages = {43-50},
	publisher = {Kluwer, Academic Publishers},
	organization = {Kluwer, Academic Publishers},
	issn = {0-7923-1500-6},
	author = {G. Vouros and C.D. Spyropoulos}
}
