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Priority claimed from CA000396947Aexternal-prioritypatent/CA1204428A/en
Priority claimed from CA000396949Aexternal-prioritypatent/CA1159442A/en
Application filed by Drill Systems IntfiledCriticalDrill Systems Int
Priority claimed from EP19850106086external-prioritypatent/EP0165479B1/en
Application grantedgrantedCritical
Publication of ATE49453T1publicationCriticalpatent/ATE49453T1/en