May Human Beings Hear It! The Mystery of the Christmas Conference Prokofieff Sergei O. Heftet / 2014 / Engelsk
Guardian of the Threshold and the Philosophy of Freedom On the Relationship of the Philosophy of Freedom to the Fifth Gospel Prokofieff Sergei O. Heftet / 2011 / Engelsk
Anthroposophy and the Philosophy of Freedom Anthroposophy and Its Method of Cognition, the Christological and Cosmic-human Dimension of the Philosophy of Freedom Prokofieff Sergei O. Heftet / 2009 / Engelsk
