@article{1104162273,
author = {\'Swi\k atek, Grzegorz},
title = {Rational rotation numbers for maps of the circle},
journal = {Comm. Math. Phys.},
volume = {113},
number = {4},
year = {1988},
pages = { 109-128},
language = {en},
url = {http://dml.mathdoc.fr/item/1104162273}
}
Świątek, Grzegorz. Rational rotation numbers for maps of the circle. Comm. Math. Phys., Tome 113 (1988) no. 4, pp. 109-128. http://gdmltest.u-ga.fr/item/1104162273/