TY  - JOUR
AU  - E. S. Lyapin
TI  - Semigroups of directed transformations of ordered sets
JO  - Sbornik. Mathematics
PY  - 1967
SP  - 33
EP  - 39
VL  - 3
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SM_1967_3_1_a2/
LA  - en
ID  - SM_1967_3_1_a2
ER  -