@article{AL_1991_30_1_a8,
     author = {Yu. D. Shmidt},
     title = {Densely simple sets with retraceable complements},
     journal = {Algebra i logika},
     pages = {106--117},
     year = {1991},
     volume = {30},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1991_30_1_a8/}
}