@article{10_4064_ap79_2_8,
     author = {Qigui Yang},
     title = {Interval oscillation criteria for second order
  self-adjoint matrix differential systems with damping},
     journal = {Annales Polonici Mathematici},
     pages = {185--198},
     publisher = {mathdoc},
     volume = {79},
     number = {2},
     year = {2002},
     doi = {10.4064/ap79-2-8},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap79-2-8/}
}