@article{bwmeta1.element.bwnjournal-article-smv20i1p19bwm, author = {S. Hartman}, title = {\"Uber Niveaulinien fastperiodischer Funktionen}, journal = {Studia Mathematica}, volume = {21}, year = {1961}, pages = {313-325}, language = {de}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-smv20i1p19bwm} }
Hartman, S. Über Niveaulinien fastperiodischer Funktionen. Studia Mathematica, Tome 21 (1961) pp. 313-325. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-smv20i1p19bwm/