@article{RM_2009_64_4_a1,
     author = {P. G. Grinevich and S. P. Novikov},
     title = {Singular finite-gap operators and indefinite metrics},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {625--650},
     publisher = {mathdoc},
     volume = {64},
     number = {4},
     year = {2009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_2009_64_4_a1/}
}