1. Conservation of the soil Creator: Gustafson, Axel Ferdinand, 1880- Collection: Core Historical Literature of Agriculture Publisher: McGraw-Hill, Publication Place: London : Date: 1937 Format: Book
2. Soil conservation Creator: Bennett, Hugh H. 1881-1960. Collection: Core Historical Literature of Agriculture Publisher: McGraw-Hill Book Company, Inc., Publication Place: London : Date: 1939 Format: Book