@article{JIS_2010__13_4_a6,
     author = {Wildberger,  N.J.},
     title = {Pell's equation without irrational numbers},
     journal = {Journal of integer sequences},
     year = {2010},
     volume = {13},
     number = {4},
     zbl = {1278.11041},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2010__13_4_a6/}
}