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@article{PORMA_1979__38_1-2_115372, author = {Cheng, Sui-Sun}, title = {Sturmian theorems for components of coupled elliptic systems}, journal = {Portugaliae mathematica}, pages = {113--117}, publisher = {mathdoc}, volume = {38}, number = {1-2}, year = {1979}, mrnumber = {0682359}, zbl = {0517.35006}, language = {en}, url = {http://geodesic.mathdoc.fr/item/PORMA_1979__38_1-2_115372/} }
Cheng, Sui-Sun. Sturmian theorems for components of coupled elliptic systems. Portugaliae mathematica, Tome 38 (1979) no. 1-2, pp. 113-117. http://geodesic.mathdoc.fr/item/PORMA_1979__38_1-2_115372/