@article{JIS_2009__12_6_a7,
     author = {Matthews,  Keith R.},
     title = {Unisequences and nearest integer continued fraction midpoint criteria for {Pell's} equation},
     journal = {Journal of integer sequences},
     year = {2009},
     volume = {12},
     number = {6},
     zbl = {1201.11011},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JIS_2009__12_6_a7/}
}