@article{DAN_1958_118_4_a1,
     author = {P. G. Kogoniya},
     title = {Condensation points of the set of {Markoff} numbers},
     journal = {Doklady Akademii Nauk},
     pages = {632--635},
     publisher = {mathdoc},
     volume = {118},
     number = {4},
     year = {1958},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1958_118_4_a1/}
}