Kussmaul 's online encyclopedic database cross-referenced topics by employing an early example of hypertext .
In 1980 , Kussmaul developed the Kussmaul Encyclopedia which came complete with its own computer system .
Kussmaul Encyclopedia 's online encyclopedic database cross-referenced topics by employing an early example of hypertext .
In 1980 , Kussmaul developed the Kussmaul Encyclopedia which came complete with its own computer system .