Instruction and study (2) Pruning (2) Varieties (2) Adaptation (2) Production (Economic theory) (2) Households (2) Foreign exchange (2) Farm produce (2) Cycles (2) Credit (2) Corn (2) Cooperative societies (2) Chronology, Historical (2) Authors (2) Management (2) Yields (2) Age (2) Sowing (2) Soils (2) Practice (2) Cronología histórica (2) Siembra (2) Cambio exterior (2) Escritores (2) Cooperativas (2) Poda (2) Producción (2) Crédito (2) Suelos (2) Productos agrícolas (2)