@article{CMH_1977__52_139713,
     author = {Robert Osserman},
     title = {A note on {Hayman's} theorem on the bass note of a drum.},
     journal = {Commentarii mathematici Helvetici},
     pages = {545--556},
     publisher = {mathdoc},
     volume = {52},
     year = {1977},
     zbl = {0374.52008},
     url = {http://geodesic.mathdoc.fr/item/CMH_1977__52_139713/}
}