TY  - JOUR
AU  - Umar, A.
TI  - Combinatorial results for semigroups of orientation-preserving partial transformations.
JO  - Journal of integer sequences
PY  - 2011
VL  - 14
IS  - 7
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/JIS_2011__14_7_a7/
LA  - en
ID  - JIS_2011__14_7_a7
ER  -