Simplify the following text for a Grade 14 native English-speaking person.
Original: His habilitation work was entitled , ' ( published in English translation in 1989 as The Structural Transformation of the Public Sphere : an Inquiry into a Category of Bourgeois Society ) .
Simplified: His habilitation work was entitled , ' ( published in English in 1989 titled The Structural Transformation of the Public Sphere : an Inquiry into a Category of Bourgeois Society ) .