@article{KYB_1993__29_3_a4,
     author = {Liu, W. B. and Rubio, J. E.},
     title = {A unified optimality condition for eigenvalue problems},
     journal = {Kybernetika},
     pages = {249--255},
     publisher = {mathdoc},
     volume = {29},
     number = {3},
     year = {1993},
     mrnumber = {1231870},
     zbl = {0790.49026},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/KYB_1993__29_3_a4/}
}