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@article{PMF_1949_47_1_a4, author = {Biernacki, Mieczys{\l}aw}, title = {Sur l'\'equation {\ensuremath{\Delta}y{\texttwosuperior}/h{\texttwosuperior}} + {A(x)y} = 0}, journal = {Prace Matematyczno-Fizyczne}, pages = {49--60}, publisher = {mathdoc}, volume = {47}, number = {1}, year = {1949}, language = {fr}, url = {http://geodesic.mathdoc.fr/item/PMF_1949_47_1_a4/} }
Biernacki, Mieczysław. Sur l'équation Δy²/h² + A(x)y = 0. Prace Matematyczno-Fizyczne, Tome 47 (1949) no. 1, pp. 49-60. http://geodesic.mathdoc.fr/item/PMF_1949_47_1_a4/