@article{AFM_2001_26_2_a6,
     author = {A. F. Beardon},
     title = {The hyperbolic metric of a rectangle},
     journal = {Annales Fennici Mathematici},
     pages = {401--407},
     publisher = {mathdoc},
     volume = {26},
     number = {2},
     year = {2001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AFM_2001_26_2_a6/}
}