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公开(公告)号:US2798025A
公开(公告)日:1957-07-02
申请号:US33722153
申请日:1953-02-16
Applicant: NAT RES DEV
Inventor: CALVERT SPENSLEY PHILIP
公开(公告)号:US2798025A
公开(公告)日:1957-07-02
申请号:US33722153
申请日:1953-02-16
Applicant: NAT RES DEV
Inventor: CALVERT SPENSLEY PHILIP