@article{10_14708_cm_v12i2_5150,
     author = {E. \'Sliwi\'nski},
     title = {On some estimation of the first eigenvalue of the membrane equation},
     journal = {Commentationes Mathematicae},
     pages = { 273--276},
     publisher = {mathdoc},
     volume = {12},
     number = {2},
     year = {1969},
     doi = {10.14708/cm.v12i2.5150},
     language = {pl},
     url = {http://geodesic.mathdoc.fr/articles/10.14708/cm.v12i2.5150/}
}