Semi-classical analysis for Harper's equation. III : Cantor structure of the spectrum
Mémoires de la Société Mathématique de France, no. 39 (1989), 132 p. 
@book{MSMF_1989_2_39__1_0,
     author = {Helffer, Bernard and Sj\"ostrand, Johannes},
     title = {Semi-classical analysis for Harper's equation. III : Cantor structure of the spectrum},
     series = {M\'emoires de la Soci\'et\'e Math\'ematique de France},
     publisher = {Soci\'et\'e math\'ematique de France},
     number = {39},
     year = {1989},
     doi = {10.24033/msmf.346},
     zbl = {0725.34099},
     language = {en},
     url = {http://www.numdam.org/item/MSMF_1989_2_39__1_0}
}

Helffer, B.; Sjöstrand, J. Semi-classical analysis for Harper's equation. III : Cantor structure of the spectrum. Mémoires de la Société Mathématique de France, Série 2, , no. 39 (1989), 132 p. doi : 10.24033/msmf.346. http://www.numdam.org/item/MSMF_1989_2_39__1_0/

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