@article{PMF_1893_4_1_a2,
     author = {Birkenmajer, Ludwik},
     title = {O zasadniczych wzorach refrakcyi astronomiczn\'ej},
     journal = {Prace Matematyczno-Fizyczne},
     pages = {44--55},
     year = {1893},
     volume = {4},
     number = {1},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/item/PMF_1893_4_1_a2/}
}