@article{PORMA_1953__12_2_114714,
     author = {Taam, Choy-Tak},
     title = {Non-oscillation and comparison theorems of linear differential equations with complex-valued coefficients},
     journal = {Portugaliae mathematica},
     pages = {57--72},
     publisher = {mathdoc},
     volume = {12},
     number = {2},
     year = {1953},
     mrnumber = {0054115},
     zbl = {0053.38402},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1953__12_2_114714/}
}