Prof. George Vithoulkas talks about the materia medica of Arnica during one of the homoeopathic courses at Alonissos. He also describes some interesting Arnica cases he has seen in his practice and about some of the common misconceptions regarding the uses of Arnica. You can find the complete teachings of Prof. Vithoulkas at the academic e-learning program http://www.vithoulkas.edu.gr and www.vithoulkas.edu.gr/es for spanish speaking people.