-
公开(公告)号:US2143879A
公开(公告)日:1939-01-17
申请号:US9427736
申请日:1936-08-04
Applicant: HILL ALBERT E
Inventor: HILL ALBERT E
IPC: E01B11/06
CPC classification number: E01B11/06
公开(公告)号:US2143879A
公开(公告)日:1939-01-17
申请号:US9427736
申请日:1936-08-04
Applicant: HILL ALBERT E
Inventor: HILL ALBERT E
IPC: E01B11/06
CPC classification number: E01B11/06