The ART-Dok Publishing Platform for Art Studies at the University Library of Heidelbergs has listed 183 books and articles by Hans Dieter Huber (25.12.2019). They are all available as downloadable PDF-files. This is a highly comfortable way to get quick and free access to the writings of Hans Dieter Huber. I highly recommend to use it.

http://archiv.ub.uni-heidelberg.de/artdok/view/schriftenreihen/sr-71.html