@inCollection{ddl1-book-96,
   author =    {Cesta, A. and Oddi, A.},
   title =     {{DDL.1: A Formal Description of a Constraint Representation Language for Physical Domains},
   booktitle = {New Directions in AI Planning},
   editor = {Ghallab, M. and Milani, A.},
   publisher = {IOS Press: Amsterdam},
   year =      1996,
}