@article{AHLV05,
 author = "M. Alpuente and M. Hanus and S. Lucas and G. Vidal", 
 title = "{Specialization of Functional Logic Programs Based on 
           Needed Narrowing}",
 journal = "Theory and Practice of Logic Programming",
 volume = 5,
 number = 3,
 pages = "273-303",
 year = "2005",
}