@article{10_4153_CJM_2000_044_2,
     author = {Urakawa, Hajime},
     title = {The {Spectrum} of an {Infinite} {Graph}},
     journal = {Canadian journal of mathematics},
     pages = {1057--1084},
     year = {2000},
     volume = {52},
     number = {5},
     doi = {10.4153/CJM-2000-044-2},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-2000-044-2/}
}