@article{ASUO_2019_XXVII_2_a9,
     author = {Mamoru Nunokawa and Janusz Sok},
     title = {On a local version of {Jack's} lemma},
     journal = {Analele Universit\u{a}\c{t}ii "Ovidius" Constan\c{t}a Seria Matematic\u{a}},
     publisher = {mathdoc},
     volume = {XXVII},
     number = {2},
     year = {2019},
     url = {http://geodesic.mathdoc.fr/item/ASUO_2019_XXVII_2_a9/}
}