@article{AIF_2005__55_1_199_0,
     author = {Friedlander, Leonid},
     title = {Extremal properties of eigenvalues for a metric graph},
     journal = {Annales de l'Institut Fourier},
     pages = {199--211},
     publisher = {Association des Annales de l{\textquoteright}institut Fourier},
     volume = {55},
     number = {1},
     year = {2005},
     doi = {10.5802/aif.2095},
     mrnumber = {2141695},
     zbl = {1074.34078},
     language = {en},
     url = {http://www.numdam.org/articles/10.5802/aif.2095/}
}