@article{MZ_1960__73_169849,
     author = {W.J. Thron and L.J. Lange},
     title = {A two-parameter family of best twin convergence regions for continued fractions.},
     journal = {Mathematische Zeitschrift},
     pages = {295--311},
     publisher = {mathdoc},
     volume = {73},
     year = {1960},
     zbl = {0094.26701},
     url = {http://geodesic.mathdoc.fr/item/MZ_1960__73_169849/}
}