Per anno

 @phdthesis {D-phdthesis,
   author       = {Denti,Enrico},
   title        = {Coordination of Heterogeneous Multi-Agent Systems: Programming the Interaction}, 
   year         = {1998},
   school       = {Dept. of Electronics, Computer Science and Systems (DEIS)
	           Viale Risorgimento 2, I-40136 Bologna, Italy},
} 

 @misc {D-phdthesisAbstract,
   author       = {Denti,Enrico},
   title        = {Coordination of Heterogeneous Multi-Agent Systems: Programming the Interaction
	           (Abstract of Ph.D. Thesis)}, 
   year         = {1998},
   howpublished = {AI*IA Notizie, Anno XI, N° 4},
   number       = {4},
   month        = {December},
}