@article{GDZPPN00206779X, title = {Small eigenvalues on Y-pieces and on Riemann surfaces.}, journal = {Commentarii mathematici Helvetici}, volume = {65}, year = {1990}, pages = {603-614}, zbl = {0752.53026}, url = {http://dml.mathdoc.fr/item/GDZPPN00206779X} }
Schmutz, Paul. Small eigenvalues on Y-pieces and on Riemann surfaces.. Commentarii mathematici Helvetici, Tome 65 (1990) pp. 603-614. http://gdmltest.u-ga.fr/item/GDZPPN00206779X/