@article{10_4064_ap_8_1_61_63,
     author = {C. Olech},
     title = {A simple proof of a certain result of {Z.} {Opial}},
     journal = {Annales Polonici Mathematici},
     pages = {61--63},
     publisher = {mathdoc},
     volume = {8},
     number = {1},
     year = {1960},
     doi = {10.4064/ap-8-1-61-63},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-8-1-61-63/}
}