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Priority claimed from FR996321Aexternal-prioritypatent/FR1423931A/fr
Priority claimed from FR2213Aexternal-prioritypatent/FR87217E/fr
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Publication of BE666494ApublicationCriticalpatent/BE666494A/fr
Procede en vue d'ameliorer de maniere permanente le drainage superficiel des terrains, de preference, des terrains couverts d'herbe, et appareil pour la mise en oeuvre de ce procede