@article{CMJ_2002__52_3_a1,
     author = {Qin, Keyun and Xu, Yang and Jun, Young Bae},
     title = {Ultra $LI$-ideals in lattice implication algebras},
     journal = {Czechoslovak Mathematical Journal},
     pages = {463--468},
     publisher = {mathdoc},
     volume = {52},
     number = {3},
     year = {2002},
     mrnumber = {1923253},
     zbl = {1012.03061},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMJ_2002__52_3_a1/}
}