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Priority claimed from DE4309233Aexternal-prioritypatent/DE4309233C1/en
Application filed by Stahl- Und Apparatebau Hans Leffer GmbhfiledCriticalStahl- Und Apparatebau Hans Leffer Gmbh
Publication of SI0690943T1publicationCriticalpatent/SI0690943T1/en
SI9430040T1993-03-231994-03-07Process and device for precisely maintaining the vertical excavation direction of a subterranean curtain
SI0690943T1
(en)