The Kacíř's hymnbook application allows you to display a parallel audiovisual content of the same book of the same name, which is the first multimedia book of its kind ever. Parallel content is displayed exclusively in virtual reality and is unreadable without using the application. Together with the printed content of the book, it forms a whole. Thanks to the application, the Heretic's Hymn Book is the first book to be written when it will be long in the hands of admirers of beautiful books or