A Dictionary of Zoology (Oxford University Press 1999) (in Danish) Engelke, S. (2006?): Til Snegleforeningen (Note to the Danish Slug-society).
A Dictionary of Zoology (Oxford University Press 1999) (en dinamarqués) Engelke, S. (2006?): Til Snegleforeningen (Nota da sociedade das lesmas dinamarquesa).