@article{DMGAA_2001_21_2_a4,
     author = {Guo, Wenbin and Shum, K.},
     title = {Minimal formations of universal algebras},
     journal = {Discussiones Mathematicae. General Algebra and Applications},
     pages = {201--205},
     publisher = {mathdoc},
     volume = {21},
     number = {2},
     year = {2001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGAA_2001_21_2_a4/}
}