@article{PORMA_1970__29_2_115111,
     author = {Jones, John jr.},
     title = {On the stability of second order differential equations},
     journal = {Portugaliae mathematica},
     pages = {81--86},
     publisher = {mathdoc},
     volume = {29},
     number = {2},
     year = {1970},
     mrnumber = {0291579},
     zbl = {0222.34028},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1970__29_2_115111/}
}