@article{MS2_1955__3_165601,
     author = {ARNE PLEIJEL},
     title = {Problem 16},
     journal = {Mathematica Scandinavica},
     pages = {306--306},
     publisher = {mathdoc},
     volume = {3},
     year = {1955},
     url = {http://geodesic.mathdoc.fr/item/MS2_1955__3_165601/}
}