@article{10_4064_cm_38_1_37_38,
     author = {E. Grzegorek},
     title = {A solution of a problem of {B.} {Rotman}},
     journal = {Colloquium Mathematicum},
     pages = {37--38},
     publisher = {mathdoc},
     volume = {38},
     number = {1},
     year = {1977},
     doi = {10.4064/cm-38-1-37-38},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-38-1-37-38/}
}