@article{VM_2014_16_2_a1,
     author = {Cristian L\u{a}zureanu},
     title = {Spirals on surfaces of revolution},
     journal = {Visual Mathematics},
     publisher = {mathdoc},
     volume = {16},
     number = {2},
     year = {2014},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/VM_2014_16_2_a1/}
}