TY  - JOUR
A1  - Brüning, Stefan
A1  - Schaub, Torsten H.
T1  - A voiding non-ground variables
Y1  - 1999
ER  - 
TY  - JOUR
A1  - Brüning, Stefan
A1  - Schaub, Torsten H.
T1  - Avoiding non-ground variables
Y1  - 1999
SN  - 3-540-66131-x
ER  -