@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/