Actually unless the comic was published before 1923 you cannot assume it is public domain. Prior to 1976 the copyright on comics was 28 years plus they could be renewed for a further 28 years giving a maximum copyright period of 56 years. However the copyright act of 1976 while extensively lengthening the period of new copyrights also added another 20 years onto any of the old copyrights still in effect on January 1, 1978. Then the Copyright Term Extension Act of 1998 (aka the Mickey Mouse Protection Act) added another 20 years onto the old still effective copyrights as well as extending the term on new copyrights. So If it was printed in 1923 or later, had the copyright renewed, it will not become public domain until 2019 at the earliest. No doubt by 2019 another ammendment will be made to ensure Mickey does not become public domain in the USA. Fortunately most GA publishers went out of business prior to the initial 28 year period being up for renewal, however with Ziff-Davis still being a publisher l was not sure, but it seems after Bill Ziff jnr took over his dads company in 1953 he decided to get out of comics and concentrate on the magazines, shortly after St. John started publishing some of the previously Ziff-Davis owned comics, so l would say the copyright was sold to them, and then they went bust, either way l do not believe the copyright on any of the Ziff-Davis comics was renewed