diff --git a/README.md b/README.md
index c9fee61618a900acd65d1e76ba055b66105f15ef..8aa5178f9452992d032bfcd37d0062817f07f50a 100644
--- a/README.md
+++ b/README.md
@@ -6,5 +6,10 @@ Richard Sowers <r-sowers@illinois.edu>, website
 
 Visualization is at <https://www.youtube.com/watch?v=J71jKkatnVc>
 
+algorithm.ipynb is main file.  It uses data.csv
+interevals.py is a dictionary;
+    key:  phone IMEI
+    value:  list of algorithmically identifies harvest intervals
+