@article{DMGAA_2012_32_1_a5,
     author = {Jampachon, Prakit and Susanti, Yeni and Denecke, Klaus},
     title = {Four-part semigroups - semigroups of {Boolean} operations},
     journal = {Discussiones Mathematicae. General Algebra and Applications},
     pages = {115--136},
     publisher = {mathdoc},
     volume = {32},
     number = {1},
     year = {2012},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/DMGAA_2012_32_1_a5/}
}