@article{10_4064_aa_78_2_153_164,
     author = {Umberto Zannier},
     title = {Remarks on a question of {Skolem} about the integer solutions of x₁x₂ - x₃x₄ = 1},
     journal = {Acta Arithmetica},
     pages = {153--164},
     publisher = {mathdoc},
     volume = {78},
     number = {2},
     year = {1996},
     doi = {10.4064/aa-78-2-153-164},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa-78-2-153-164/}
}