@article{CMUC_2005__46_2_a0,
     author = {Ad\'amek, Ji\v{r}{\'\i}},
     title = {Birkhoff's {Covariety} {Theorem} without limitations},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {197--215},
     publisher = {mathdoc},
     volume = {46},
     number = {2},
     year = {2005},
     mrnumber = {2176888},
     zbl = {1121.18003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_2005__46_2_a0/}
}