Triplanetary

US original — the Fantasy Press 1948 edition is the first appearance in book form anywhere, and the census claim is correct. There is no earlier or competing UK edition and no original-language issue elsewhere. The important trap is textual rather than geographic: the 1948 book is NOT a reissue of the 1934 Amazing Stories serial of the same name. It is a substantially rewritten fix-up retrofitted as the Lensman opener — Book One ("Dawn") and Book Two ("The World War") are new material, and only Book Three revises and expands the 1934 serial. A copy described as "the 1934 Triplanetary in book form" is misdescribed; that text had no separate book edition.