@article{ELA_2006__15__a1,
     author = {Nikiforov, Vladimir},
     title = {Linear combinations of graph eigenvalues},
     journal = {The electronic journal of linear algebra},
     pages = {329--336},
     publisher = {mathdoc},
     volume = {15},
     year = {2006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ELA_2006__15__a1/}
}