diff --git a/Lib-re.md b/Lib-re.md
index 40646d3..0f92728 100644
--- a/Lib-re.md
+++ b/Lib-re.md
@@ -26,6 +26,9 @@
     - http://en.wikipedia.org/wiki/Backtracking (not a very hard algorithm, this is sufficient)
   4. Technique: Memoized Backtracking Search
     - Discussed in Russ Cox Regexp2 above ( http://swtch.com/~rsc/regexp/regexp2.html )
+  5. Technique: OBDD NFA simulation:
+    - http://link.springer.com/chapter/10.1007%2F978-3-642-15512-3_4 (without submatch extraction)
+    - http://www.hpl.hp.com/techreports/2012/HPL-2012-215.pdf (with submatch extraction)
 
 ### Summary of research on standards and leading techniques
 
@@ -47,6 +50,8 @@ Memoized backtracking search is O(nm) time and O(nm) space. It can't implement b
 
 It is also not difficult to imagine falling back to a backtracking implementation in the presence of backreferences, if those are to be supported.
 
+<FIXME: summarize OBDD methods>
+
 #### Relevant standards and techniques exist?
 #### Those intended to follow (and why)
 #### Those intended to ignore (and why)