@article{MABA_2001_15_3-4_a5,
     author = {M. Racheva},
     title = {On {Estimating} of a {Fourth-Order} {Differential} {Equations}},
     journal = {Mathematica balkanica},
     pages = {239},
     publisher = {mathdoc},
     volume = {15},
     number = {3-4},
     year = {2001},
     url = {http://geodesic.mathdoc.fr/item/MABA_2001_15_3-4_a5/}
}