Potash and Phosphate Institute [PPI]. (1923). Better crops with plant food. PPI.
Cita Chicago Style (17a ed.)Potash and Phosphate Institute [PPI]. Better Crops with Plant Food. Norcross: PPI, 1923.
Cita MLA (8a ed.)Potash and Phosphate Institute [PPI]. Better Crops with Plant Food. PPI, 1923.
Precaución: Estas citas no son 100% exactas.