TY  - JOUR
A1  - Denecke, Klaus-Dieter
A1  - Koppitz, Jörg
T1  - Normal forms of hypersubstitutions
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Denecke, Klaus-Dieter
A1  - Koppitz, Jörg
T1  - A characterization of M-solid varieties of semigroups
Y1  - 1999
ER  -