@article{ASNSP_1979_4_6_1_19_0, author = {Klingenberg, Wilhelm}, title = {Closed geodesics on surfaces of genus 0}, journal = {Annali della Scuola Normale Superiore di Pisa - Classe di Scienze}, pages = {19--38}, publisher = {Scuola normale superiore}, volume = {Ser. 4, 6}, number = {1}, year = {1979}, zbl = {0426.58008}, mrnumber = {529474}, language = {en}, url = {http://www.numdam.org/item/ASNSP_1979_4_6_1_19_0/} }