@article{PDA_1974_5_a1,
     author = {P. Ranzinger and M. Vuki\'cevi\'c-Karabin},
     title = {On the {Structure} and the {Development} of the {Sunspot} {Group}},
     journal = {Publications of the Department of Astronomy},
     pages = {9 },
     publisher = {mathdoc},
     volume = {5},
     year = {1974},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PDA_1974_5_a1/}
}