@article{RLIN_2001_9_12_3_a4,
     author = {Villaggio, Piero},
     title = {The apparent propagation velocity of a wave},
     journal = {Atti della Accademia nazionale dei Lincei. Rendiconti Lincei. Matematica e applicazioni},
     pages = {191--197},
     publisher = {mathdoc},
     volume = {Ser. 9, 12},
     number = {3},
     year = {2001},
     zbl = {1170.80320},
     mrnumber = {1175584},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RLIN_2001_9_12_3_a4/}
}