@book{Downward1998,
	title = {Logic and Declarative Language},
	author = {Michael Downward},
	publisher = {Taylor and Francis},
	year = {1998},
	biburl = {http://www.bibsonomy.org/bibtex/2fce2a2c0a0c673b0dabe44d046074e21/evol},
	isbn = {0-7484-0802-9},
	keywords = {declarative language logic programming }
}