I would blindly believe that Eudic could have done a great job in these books considering all the dictionary data they have had at their hands. With smart use of these dictionary data, they would have been able to make very good summaries of prefixes and suffixes.
Will there be anybody who would have the interests to make a PDF of these books? I am especially interested in the German book 《德语词缀密码》, but unfortunately I am not in China. So hoping that I can get a copy of this book in PDF.