@article{10_4153_CMB_2011_159_6,
     author = {Amara, Jamel Ben},
     title = {Comparison {Theorem} for {Conjugate} {Points} of a {Fourth-order} {Linear} {Differential} {Equation}},
     journal = {Canadian mathematical bulletin},
     pages = {39--43},
     year = {2013},
     volume = {56},
     number = {1},
     doi = {10.4153/CMB-2011-159-6},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-2011-159-6/}
}