TY  - JOUR
AU  - Umar, Abdullahi
TI  - Presentations for subsemigroups of $PD_n$
JO  - Czechoslovak Mathematical Journal
PY  - 2019
SP  - 417
EP  - 426
VL  - 69
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/articles/10.21136/CMJ.2018.0343-17/
DO  - 10.21136/CMJ.2018.0343-17
LA  - en
ID  - 10_21136_CMJ_2018_0343_17
ER  -