@incollection{JEDP_2000____A17_0,
     author = {Parnovski, Leonid and Sobolev, Alexander V.},
     title = {On the {Bethe-Sommerfeld} conjecture},
     booktitle = {},
     series = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {17},
     pages = {1--13},
     publisher = {Universit\'e de Nantes},
     year = {2000},
     mrnumber = {2002i:35137},
     zbl = {01808707},
     language = {en},
     url = {http://archive.numdam.org/item/JEDP_2000____A17_0/}
}