diff --git a/src/ReportBase/_Bibliography.py b/src/ReportBase/_Bibliography.py
index 0af8b882e..82f9d4507 100644
--- a/src/ReportBase/_Bibliography.py
+++ b/src/ReportBase/_Bibliography.py
@@ -78,10 +78,10 @@ class Citation:
         second_letter = ''
         letter_count = len(string.lowercase)
         ref_count = len(self.__ref_list)
-        if ref_count > letter_count:
+        if ref_count > letter_count -1:
             # If there are more than 26 references, we need to use two 
             # characters to uniquely identify them all.
-            first_letter = string.lowercase[ ref_count / letter_count ]
+            first_letter = string.lowercase[ ref_count / letter_count -1 ]
         second_letter = string.lowercase[ ref_count % letter_count ]
         
         key = first_letter + second_letter
@@ -228,4 +228,4 @@ class Bibliography:
                 if notehandle not in nl2:
                     return False
         # Can't find anything different. They must be equal.
-        return True
\ No newline at end of file
+        return True