diff --git a/lib/bibtex/entry.rb b/lib/bibtex/entry.rb
index 68004c1..f45c09b 100644
--- a/lib/bibtex/entry.rb
+++ b/lib/bibtex/entry.rb
@@ -564,7 +564,8 @@ def pages_to
 
     # Returns true if this entry is published inside a book, collection or journal
     def contained?
-      has_field?(:booktitle, :container, :journal)
+      has_field?(:container, :journal) ||
+        has_field?(:booktitle) && get(:booktitle) != get(:title)
     end
 
     # Returns an array containing the values associated with the given keys.