@book{MSMF_1990_2_43__1_0,
     author = {Helffer, B. and Kerdelhue, P. and Sj\"ostrand, J.},
     title = {Le papillon de {Hofstadter} revisit\'e},
     series = {M\'emoires de la Soci\'et\'e Math\'ematique de France},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {43},
     year = {1990},
     doi = {10.24033/msmf.349},
     zbl = {0732.44004},
     language = {fr},
     url = {http://archive.numdam.org/item/MSMF_1990_2_43__1_0/}
}