File:Amazing0647.jpg
Source: Cover scanned by User:Hoblok and uploaded in August 2006.
Works copyrighted before 1964 had to have the copyright renewed sometime in the 28th year. If the copyright was not renewed the work is in the public domain. It is best to search 6 months before and after the required year. Some magazines are published the month before the cover date and some registrations may be delayed for a few months.
This 1947 issue of Amazing Stories would have to be renewed in 1974. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. http://onlinebooks.library.upenn.edu/cce/
The search of the Renewals for Periodicals for 1973, 1974 and 1975 show no renewal entries for Amazing Stories. Ziff-Davis Publishing owned Amazing Stories in 1947 and Ultimate Publishing Company owned it from 1965 to 1982.
The copyright on the magazine was not renewed and it is in the public domain.