@article{AM2_1993__46_2-3_137553,
     author = {T.W. Cusick},
     title = {On {Perrine's} generalized {Markoff} equation.},
     journal = {Aequationes mathematicae},
     pages = {203--211},
     publisher = {mathdoc},
     volume = {46},
     number = {2-3},
     year = {1993},
     zbl = {0813.11013},
     url = {http://geodesic.mathdoc.fr/item/AM2_1993__46_2-3_137553/}
}