@article{bwmeta1.element.bwnjournal-article-pmfv40i1p8bwm, author = {M. Biernacki}, title = {Sur l'\'equation diff\'erentielle x''+A(t)x=0}, journal = {Prace Matematyczno-Fizyczne}, volume = {40}, year = {1933}, pages = {163-171}, zbl = {0006.20001}, language = {fra}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-pmfv40i1p8bwm} }
Biernacki, M. Sur l'équation différentielle x''+A(t)x=0. Prace Matematyczno-Fizyczne, Tome 40 (1933) pp. 163-171. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-pmfv40i1p8bwm/