@article{GDZPPN002073528,
title = {\"Uber die nat\"urliche Gleichung R(s) = ...a (... + cos...).},
journal = {Elemente der Mathematik},
volume = {9},
year = {1954},
pages = {56-63},
zbl = {0056.14901},
url = {http://dml.mathdoc.fr/item/GDZPPN002073528}
}
Klepper, W. Über die natürliche Gleichung R(s) = ...a (... + cos...).. Elemente der Mathematik, Tome 9 (1954) pp. 56-63. http://gdmltest.u-ga.fr/item/GDZPPN002073528/