@book{HLR98,
author = {M.T.~Hortal\'{a}-Gonz\'{a}lez and J.~Leach-Albert and M.~Rodr\'{\i}guez-Artalejo},
publisher = {Editorial Complutense},
title = {Matem\'{a}tica Discreta y L\'{o}gica Matem\'{a}tica},
projects = {},
butype = {book},
year = {1998}
}