Tymn, Michael Egon. “Communication With The Spirit World of God: Its Laws and Purpose. Extraordinary Experiences of a Catholic Priest by Johannes Greber”. Journal of Scientific Exploration 27, no. 4 (February 20, 2014). Accessed May 15, 2024. https://www.journalofscientificexploration.org/index.php/jse/article/view/657.