@article{AUPO_2005__44_1_a2,
     author = {Chajda, Ivan},
     title = {Sheffer operation in ortholattices},
     journal = {Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica},
     pages = {19--23},
     publisher = {mathdoc},
     volume = {44},
     number = {1},
     year = {2005},
     mrnumber = {2218564},
     zbl = {1091.06007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUPO_2005__44_1_a2/}
}