@article{AFM_1979_4_1_a13,
     author = {Timo Ravaska},
     title = {Frenet theory of surfaces},
     journal = {Annales Fennici Mathematici},
     pages = {151--168},
     publisher = {mathdoc},
     volume = {4},
     number = {1},
     year = {1979},
     doi = {10.5186/aasfm.1978-79.0421},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.5186/aasfm.1978-79.0421/}
}