@incollection{JEDP_1990____A20_0,
     author = {Fr\'ed\'eric Klopp},
     title = {Impuret\'es dans une structure p\'eriodique},
     booktitle = {},
     series = {Journ\'ees \'equations aux d\'eriv\'ees partielles},
     eid = {20},
     pages = {1--12},
     publisher = {\'Ecole polytechnique},
     year = {1990},
     zbl = {0707.35125},
     mrnumber = {91k:35184},
     language = {fr},
     url = {https://proceedings.centre-mersenne.org/item/JEDP_1990____A20_0/}
}