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公开(公告)号:US840744A
公开(公告)日:1907-01-08
申请号:US1906321813
申请日:1906-06-15
Applicant: BOOF MICHAEL
Inventor: BOOF MICHAEL
CPC classification number: E21B25/04
公开(公告)号:US840744A
公开(公告)日:1907-01-08
申请号:US1906321813
申请日:1906-06-15
Applicant: BOOF MICHAEL
Inventor: BOOF MICHAEL
CPC classification number: E21B25/04