@article{10_4064_ba57_2_7,
     author = {A. El-Haffaf},
     title = {Existence {Theorems} for a {Fourth} {Order} {Boundary} {Value} {Problem}},
     journal = {Bulletin of the Polish Academy of Sciences. Mathematics},
     pages = {135--148},
     publisher = {mathdoc},
     volume = {57},
     number = {2},
     year = {2009},
     doi = {10.4064/ba57-2-7},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ba57-2-7/}
}