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公开(公告)号:US2190547A
公开(公告)日:1940-02-13
申请号:US14136737
申请日:1937-05-07
Applicant: DAVID ERICKSON
Inventor: LE BUS JOHN E
IPC: E21B19/16
公开(公告)号:US2190547A
公开(公告)日:1940-02-13
申请号:US14136737
申请日:1937-05-07
Applicant: DAVID ERICKSON
Inventor: LE BUS JOHN E
IPC: E21B19/16