Sec. 20. That where the copyright proprietor has sought to comply with the provisions of this Act with respect to notice, the omission by accident or mistake of the prescribed notice from a particular copy or copies shall not invalidate the copyright or prevent recovery for infringement against any person who, after actual notice of the copyright, begins an undertaking to infringe it, but shall prevent the recovery of damages against an innocent infringer, who has been misled by the omission of the notice; and in a suit for infringement no permanent injunction shall be had unless the copyright proprietor shall reimburse to the innocent infringer his reasonable outlay, innocently incurred, if the court, in its discretion, shall so direct.
Sec. 21. That in the case of a book published abroad in the English language before publication in this country, the deposit in the copyright office, not later than thirty days after its publication abroad, of one complete copy of the foreign edition, with a request for the reservation of the copyright and a statement of the name and nationality of the author and of the copyright proprietor and of the date of publication of the said book, shall secure to the author or proprietor an ad interim copyright, which shall have all the force and effect given to copyright by this Act, and shall endure until the expiration of thirty days after such deposit in the copyright office.
Sec. 22. That whenever within the period of such ad interim protection an authorized edition of such book shall be published within the United States, in accordance with the manufacturing provisions specified in section fifteen of this Act, and whenever the provisions of this Act as to deposit of copies, registration, filing of affidavit, and the printing of the copyright notice shall have been duly complied with, the copyright shall be extended to endure in such book for the full term elsewhere provided in this Act.
Sec. 23. That the copyright secured by this Act shall endure for twenty-eight years from the date of first publication, whether the copyrighted work bears the author's true name or is published anonymously or under an assumed name: Provided, That in the case of any posthumous work or of any periodical, cyclopaedic, or other composite work upon which the copyright was originally secured by the proprietor thereof, or of any work copyrighted by a corporate body (otherwise than as assignee or licensee of the individual author) or by an employer for whom such work is made for hire, the proprietor of such copyright shall be entitled to a renewal and extension of the copyright in such work for the further term of twenty-eight years when application for such renewal and extension shall have been made to the copyright office and duly registered therein within one year prior to the expiration of the original term of copyright: And provided further, That in the case of any other copyrighted work, including a contribution by an individual author to a periodical or to a cyclopaedic or other composite work when such contribution has been separateately registered, the author of such work, if still living, or the widow, widower, or children of the author, if the author be not living, or if such author, widow, widower, or children be not living, then the author's executors, or in the absence of a will, his next of kin shall be entitled to a renewal and extension of the copyright in such work for a further term of twenty-eight years when application for such renewal and extension shall have been made to the copyright office and duly registered therein within one year prior to the expiration of the original term of copyright: And provided further, That in default of the registration of such application for renewal and extension, the copyright in any work shall determine at the expiration of twenty-eight years from first publication.
Sec. 24. That the copyright subsisting in any work at the time when this Act goes into effect may, at the expiration of the term