@article{MM2_1972__7_154124,
     author = {Roland Zielke},
     title = {A {Remark} on {Periodic} {Tchebyshev} {Systems.}},
     journal = {Manuscripta mathematica},
     pages = {325--330},
     publisher = {mathdoc},
     volume = {7},
     year = {1972},
     zbl = {0239.42024},
     url = {http://geodesic.mathdoc.fr/item/MM2_1972__7_154124/}
}