Every now and then materials become from the book literature after a treatment by theatre authors (Dramatisierung) brought on the stage. Examples are the working on of the works of Karl May for the Karl May plays on different stages.
Theatres acquire the right to convert a certain piece of a theatre author shortened or unabridged into a stage work. The theatre director has thereby the task, the text into bring an action on the stage. Every now and then this conversion takes place via the author.