1 Introduction  
1.1 “Explanation” Needs Explanation  
1.2 Motivation for a Systematic Review  

2 Defining ANN-CBR Twins  
2.1 ANN-CBR Twins  

3 A Systematic Review: Methodology  
3.1 Method: Search Procedure  
3.2 Results Summary  

4 A History of ANN-CBR Twins  

5 Future Directions: Road Mapping