@article{10_1017_S0017089500001415,
     author = {Bradley, John S.},
     title = {Comparison theorems for the square integrability of solutions of (r(t)y')'+q(t)y=f(t, y)},
     journal = {Glasgow mathematical journal},
     pages = {75--79},
     year = {1972},
     volume = {13},
     number = {1},
     doi = {10.1017/S0017089500001415},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500001415/}
}