Não informado. (1960). Technical communication. Department of Agriculture and Water Supply.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Technical Communication. Pretoria, Africa do Sul: Department of Agriculture and Water Supply, 1960.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Technical Communication. Department of Agriculture and Water Supply, 1960.
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