'The Master Mind of Mars' is an Edgar Rice Burroughs science fiction novel, the sixth of his famous Barsoom series. It was first published in the magazine Amazing Stories Annual vol. 1, July 15, 1927. The first book edition was published by A. C. McClurg in March, 1928.
The author died in 1950, so this work is also in the public domain in countries and areas where the copyright term is the author's life plus 70 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 1927 would have had to renew their copyright in either 1954 or 1955, i.e. at least 27 years after it was first published / registered but not later than in the 28th year. As it was not renewed, it entered the public domain on .