@article{SM_2007_198_11_a2,
     author = {I. M. Guseinov and I. M. Nabiev},
     title = {The inverse spectral problem for pencils
},
     journal = {Sbornik. Mathematics},
     pages = {1579--1598},
     publisher = {mathdoc},
     volume = {198},
     number = {11},
     year = {2007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2007_198_11_a2/}
}