@article{AUM_2012_66_1_a0,
     author = {Cie\'slak, Waldemar and Szczygielska, Elzbieta},
     title = {Affine invariants of annuli},
     journal = {Annales Universitatis Mariae Curie-Sk{\l}odowska. Mathematica },
     publisher = {mathdoc},
     volume = {66},
     number = {1},
     year = {2012},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUM_2012_66_1_a0/}
}