diff --git a/src/calibre/ebooks/metadata/sources/amazon.py b/src/calibre/ebooks/metadata/sources/amazon.py
index 24df68e51d..8483698e28 100644
--- a/src/calibre/ebooks/metadata/sources/amazon.py
+++ b/src/calibre/ebooks/metadata/sources/amazon.py
@@ -301,7 +301,7 @@ class Amazon(Source):
         if asin is None:
             asin = identifiers.get('asin', None)
         if asin:
-            return 'http://amzn.com/%s'%asin
+            return ('amazon', asin, 'http://amzn.com/%s'%asin)
     # }}}
 
     def create_query(self, log, title=None, authors=None, identifiers={}): # {{{
diff --git a/src/calibre/ebooks/metadata/sources/base.py b/src/calibre/ebooks/metadata/sources/base.py
index eb0277bd3f..f386489fcd 100644
--- a/src/calibre/ebooks/metadata/sources/base.py
+++ b/src/calibre/ebooks/metadata/sources/base.py
@@ -374,7 +374,11 @@ class Source(Plugin):
 
     def get_book_url(self, identifiers):
         '''
-        Return the URL for the book identified by identifiers at this source.
+        Return a 3-tuple or None. The 3-tuple is of the form:
+        (identifier_type, identifier_value, URL).
+        The URL is the URL for the book identified by identifiers at this
+        source. identifier_type, identifier_value specify the identifier
+        corresponding to the URL.
         This URL must be browseable to by a human using a browser. It is meant
         to provide a clickable link for the user to easily visit the books page
         at this source.
diff --git a/src/calibre/ebooks/metadata/sources/google.py b/src/calibre/ebooks/metadata/sources/google.py
index 4133d4d527..b479368bac 100644
--- a/src/calibre/ebooks/metadata/sources/google.py
+++ b/src/calibre/ebooks/metadata/sources/google.py
@@ -173,7 +173,7 @@ class GoogleBooks(Source):
     def get_book_url(self, identifiers): # {{{
         goog = identifiers.get('google', None)
         if goog is not None:
-            return 'http://books.google.com/books?id=%s'%goog
+            return ('google', goog, 'http://books.google.com/books?id=%s'%goog)
     # }}}
 
     def create_query(self, log, title=None, authors=None, identifiers={}): # {{{
diff --git a/src/calibre/ebooks/metadata/sources/identify.py b/src/calibre/ebooks/metadata/sources/identify.py
index 8771274f92..335d741fd2 100644
--- a/src/calibre/ebooks/metadata/sources/identify.py
+++ b/src/calibre/ebooks/metadata/sources/identify.py
@@ -438,14 +438,13 @@ def urls_from_identifiers(identifiers): # {{{
     ans = []
     for plugin in all_metadata_plugins():
         try:
-            url = plugin.get_book_url(identifiers)
-            if url is not None:
-                ans.append((plugin.name, url))
+            id_type, id_val, url = plugin.get_book_url(identifiers)
+            ans.append((plugin.name, id_type, id_val, url))
         except:
             pass
     isbn = identifiers.get('isbn', None)
     if isbn:
-        ans.append((isbn,
+        ans.append((isbn, 'isbn', isbn,
             'http://www.worldcat.org/search?q=bn%%3A%s&qt=advanced'%isbn))
     return ans
 # }}}
diff --git a/src/calibre/gui2/metadata/single_download.py b/src/calibre/gui2/metadata/single_download.py
index 06ea8cf76a..cc89ef2259 100644
--- a/src/calibre/gui2/metadata/single_download.py
+++ b/src/calibre/gui2/metadata/single_download.py
@@ -253,7 +253,7 @@ class ResultsView(QTableView): # {{{
         parts.append('</center>')
         if book.identifiers:
             urls = urls_from_identifiers(book.identifiers)
-            ids = ['<a href="%s">%s</a>'%(url, name) for name, url in urls]
+            ids = ['<a href="%s">%s</a>'%(url, name) for name, ign, ign, url in urls]
             if ids:
                 parts.append('<div><b>%s:</b> %s</div><br>'%(_('See at'), ', '.join(ids)))
         if book.tags: