It's listed at the
US Government Bookstore as being published by the Defense Department, author Louis Morton, published in 1962.
If it was a work for hire, it's a US government publication, and so in the public domain.
If it was copyright by the author, the copyright must have been renewed in 1990 or so to retain its copyright, and there's no renewal record at the US Copyright Office.
I think it's safe for you to produce an ePub version, although, of course, IANAL.