@article{MZM_1968_4_3_a13,
     author = {M. K. Gol'dberg and \'E. M. Livshits},
     title = {On minimal universal trees},
     journal = {Matemati\v{c}eskie zametki},
     pages = {371--380},
     publisher = {mathdoc},
     volume = {4},
     number = {3},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1968_4_3_a13/}
}