code: protected List<Reference> mergeReferences(
  			List<? extends Reference> references1,
  			List<? extends Reference> references2) {
  		List<Reference> result = new ArrayList<>();
  		for (Reference reference : references1) {
  			addBestReferenceToList(reference, result);
  		}
  		for (Reference reference : references2) {
  			addBestReferenceToList(reference, result);
  		}
  		return result;
  	}
docs: Merges two lists of references, eliminating duplicates in the process.
  
  @param references1
  @param references2
  @return merged list