@article{MZM_1976_19_1_a8,
     author = {V. M. Kopytov and N. Ya. Medvedev},
     title = {Linearly ordered groups whose system of convex subgroups is central},
     journal = {Matemati\v{c}eskie zametki},
     pages = {85--90},
     publisher = {mathdoc},
     volume = {19},
     number = {1},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1976_19_1_a8/}
}