@article{IM_1973__22_142241,
     author = {Louis Block and John Franke},
     title = {Existence of {Periodic} {Points} of {Maps} of {S1.}},
     journal = {Inventiones mathematicae},
     pages = {69},
     publisher = {mathdoc},
     volume = {22},
     year = {1973},
     zbl = {0272.58005},
     language = {un},
     url = {https://geodesic-test.mathdoc.fr/item/IM_1973__22_142241/}
}