TY  - BOOK
AU  - Hughes,G.E.
AU  - Londey,D.G.
TI  - The Elements of formal logic / 
U1  - 160 
PY  - 1965///
CY  - London
PB  - Methuen
KW  - Logic
N1  - Includes index; Bibliography : p. 386-388
ER  -