@article{ZNSL_2003_300_a20,
     author = {V. L. Oleinik and B. S. Pavlov},
     title = {Embedded spectrum on a~metric graph (an observation)},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {215--220},
     publisher = {mathdoc},
     volume = {300},
     year = {2003},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2003_300_a20/}
}