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Priority to JP2718784UpriorityCriticalpatent/JPS60140602U/ja
Publication of JPS60140602UpublicationCriticalpatent/JPS60140602U/ja
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Publication of JPS64968Y2publicationCriticalpatent/JPS64968Y2/ja
A method of permanently improving the surface drainage from ground fields, preferably grass-covered fields, as well as an apparatus for use by the method