@article{JMAG_2018_14_a2,
     author = {Thomas Kappeler and Yannick Widmer},
     title = {On spectral properties of the $L$ operator in the {Lax} pair of the {sine-Gordon} equation},
     journal = {\v{Z}urnal matemati\v{c}eskoj fiziki, analiza, geometrii},
     pages = {452--509},
     publisher = {mathdoc},
     volume = {14},
     year = {2018},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JMAG_2018_14_a2/}
}