@article{JEDP_1998____A15_0,
     author = {Zelditch, Steve},
     title = {Normal form of the wave group and inverse spectral theory},
     journal = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {15},
     pages = {1--18},
     publisher = {Universit\'e de Nantes},
     year = {1998},
     mrnumber = {99h:58197},
     zbl = {01808724},
     language = {en},
     url = {http://www.numdam.org/item/JEDP_1998____A15_0/}
}