@article{AUPO_1978_17_1_a7,
     author = {Rach\r{u}nkov\'a, Irena},
     title = {Algebraic properties of phases of the differential equation $y'=q(t)y$},
     journal = {Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica},
     pages = {69--76},
     year = {1978},
     volume = {17},
     number = {1},
     mrnumber = {0554038},
     zbl = {0423.34013},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUPO_1978_17_1_a7/}
}