TY  - DATA
AU  - Craig, William
TI  - Semigroups underlying first-order logic 
T2  - Memoirs of the American Mathematical Society, 
SN  - 9781470404703 (online)
PY  - 2006///
CY  - Providence, R.I.
PB  - American Mathematical Society
UR  - http://www.ams.org/memo/0866
ER  -