TY  - JOUR
AU  - G. S. Makanin
TI  - On the rank of coefficientless equations in four unknowns in a~free semigroup
JO  - Sbornik. Mathematics
PY  - 1976
SP  - 257
EP  - 280
VL  - 29
IS  - 2
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/SM_1976_29_2_a9/
LA  - en
ID  - SM_1976_29_2_a9
ER  -