@article{ADM_2021_32_2_a10,
     author = {A. Umar},
     title = {On certain semigroups of contraction mappings of a~finite chain},
     journal = {Algebra and discrete mathematics},
     pages = {299--320},
     publisher = {mathdoc},
     volume = {32},
     number = {2},
     year = {2021},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ADM_2021_32_2_a10/}
}