TY  - BOOK
AU  - Gray, John,
TI  - The social system: A treatise on the principles of exchange 
AV  - HB161 G73
PY  - 1972///
CY  - New York
PB  - Kraus
KW  - Economía
N1  - Facsimil de: edinburgh : william tait, 1831
ER  -