@article{MS2_1984__54_166875,
     author = {Pekka Neittaanm\"aki and Michal Kr{\'\i}zek},
     title = {On the validity of {Friedrichs'} inequalities.},
     journal = {Mathematica Scandinavica},
     pages = {17--26},
     publisher = {mathdoc},
     volume = {54},
     year = {1984},
     zbl = {0555.35003},
     url = {http://geodesic.mathdoc.fr/item/MS2_1984__54_166875/}
}