I have attached a list of my publications.  Apologies that it hasn't been cleaned up; you are probably much better going to Google Scholar and going to my profile. But there are plenty of other researchers who have written excellent papers about RDR.  I think the most prolific is Byeong Kang, the co-author on the RDR book.  His Google scholar profile is here.  You will find other authors if you search for "Ripple-Down Rules"  or "RDR knowledge acquisition"; you need some sort of qualifier with RDR as the term is also used with quite other meanings.  You will also find a lot of papers that are not about RDR knowledge acquisition, but have used RIDOR as a standard machine learning algorithm.  RIDOR is part of the WEKA ML workbench and is based on Brian Gaines Induct-RDR.  You might add a term like "-RIDOR" or "-WEKA", but this will exclude a few papers; you just have to play around :-)