@article{10_4064_sm_81_3_293_302,
     author = {Rafa{\l} Ko{\l}odziej},
     title = {The rotation number of some transformation related to billiards in an ellipse},
     journal = {Studia Mathematica},
     pages = {293--302},
     publisher = {mathdoc},
     volume = {81},
     number = {3},
     year = {1985},
     doi = {10.4064/sm-81-3-293-302},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm-81-3-293-302/}
}