The author died in 1961, so this work is also in the public domain in countries and areas where the copyright term is the author's life plus 50 years or less. This work may also be in the public domain in countries and areas with longer native copyright terms that apply the rule of the shorter term to foreign works.
Works published in 1958 would have had to renew their copyright in either 1985 or 1986, i.e. at least 27 years after it was first published / registered but not later than 31 December(31 December) in the 28th year. As it was not renewed, it entered the public domain on 1 January 1987(1 January 1987).