diff --git a/caliGraph.py b/caliGraph.py
index 0008ae5..fc13fde 100755
--- a/caliGraph.py
+++ b/caliGraph.py
@@ -961,7 +961,7 @@ def shell(G, books, mu, std):
     embed(globals(), locals())
 
 def newBooks(G, books, num, mu, std):
-    removeBad(G, mu+std)
+    removeBad(G, mu-std*2)
     findNewBooks(G, books, num, minRecSco = mu-std)
     removeUnread(G)
     removeUselessReadBooks(G)