@article{AA_2005_17_5_a6,
     author = {M. Z. Solomyak},
     title = {A~mathematical model for a~noninvertible quantum graph},
     journal = {Algebra i analiz},
     pages = {190--231},
     year = {2005},
     volume = {17},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AA_2005_17_5_a6/}
}