@article{10_4064_ap82_1_10,
     author = {Qi-Ru Wang},
     title = {Interval criteria for oscillation of second order
 self-adjoint matrix differential systems},
     journal = {Annales Polonici Mathematici},
     pages = {87--93},
     publisher = {mathdoc},
     volume = {82},
     number = {1},
     year = {2003},
     doi = {10.4064/ap82-1-10},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap82-1-10/}
}