@article{10_4153_CMB_1992_043_9,
     author = {Day, Alan and Nation, J. B.},
     title = {Congruence {Normal} {Covers} of {Finitely} {Generated} {Lattice} {Varieties}},
     journal = {Canadian mathematical bulletin},
     pages = {311--320},
     year = {1992},
     volume = {35},
     number = {3},
     doi = {10.4153/CMB-1992-043-9},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1992-043-9/}
}