31. Volume 21, Number 2: Plant world Collection: Core Historical Literature of Agriculture Publisher: Plant World Association Publication Place: Baltimore, Md. Date: 1918 Format: Issue
32. Volume 21, Number 3: Plant world Collection: Core Historical Literature of Agriculture Publisher: Plant World Association Publication Place: Baltimore, Md. Date: 1918 Format: Issue
33. Volume 21, Number 4: Plant world Collection: Core Historical Literature of Agriculture Publisher: Plant World Association Publication Place: Baltimore, Md. Date: 1918 Format: Issue
34. Volume 21, Number 5: Plant world Collection: Core Historical Literature of Agriculture Publisher: Plant World Association Publication Place: Baltimore, Md. Date: 1918 Format: Issue
35. Volume 21, Number 6: Plant world Collection: Core Historical Literature of Agriculture Publisher: Plant World Association Publication Place: Baltimore, Md. Date: 1918 Format: Issue
36. Volume 21, Number 7: Plant world Collection: Core Historical Literature of Agriculture Publisher: Plant World Association Publication Place: Baltimore, Md. Date: 1918 Format: Issue
37. Volume 21, Number 8: Plant world Collection: Core Historical Literature of Agriculture Publisher: Plant World Association Publication Place: Baltimore, Md. Date: 1918 Format: Issue
38. Volume 21, Number 9: Plant world Collection: Core Historical Literature of Agriculture Publisher: Plant World Association Publication Place: Baltimore, Md. Date: 1918 Format: Issue
39. Volume 20, Index : Plant world Collection: Core Historical Literature of Agriculture Publisher: Plant World Association Publication Place: Baltimore, Md. Date: 1917 Format: Issue
40. Volume 20, Number 10: Plant world Collection: Core Historical Literature of Agriculture Publisher: Plant World Association Publication Place: Baltimore, Md. Date: 1917 Format: Issue
