Obviously if the author invite you to copy their book they are aware that it is not stealing, so I think it's a reference to Abbie Hoffman's book (https://en.wi

Obviously if the author invite you to copy their book they are aware that it is not stealing, so I think it's a reference to Abbie Hoffman's book (https://en.wikipedia.org/wiki/Steal_This_Book https://en.wikipedia.org/wiki/Steal_This_Book).