@article{CMUC_2009__50_2_a6,
     author = {Crainic, Marius and Crainic, Nicolae},
     title = {Normal bivariate {Birkhoff} interpolation schemes and {Pell} equation},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {265--272},
     publisher = {mathdoc},
     volume = {50},
     number = {2},
     year = {2009},
     mrnumber = {2537835},
     zbl = {1212.65040},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_2009__50_2_a6/}
}