diff --git a/Extract.hs b/Extract.hs
--- a/Extract.hs
+++ b/Extract.hs
@@ -24,25 +24,40 @@
 import qualified Data.Text.Lazy as T
 import qualified Data.ByteString.Lazy.Char8 as B
 import Control.Applicative
+import Safe(headMay,tailMay)
 
 import Entry
 
+
 openURL x = return . T.pack =<<  getResponseBody =<< simpleHTTP (getRequest x)
 
 getTags :: Text -> IO [Tag Text]
 getTags url = parseTags <$> openURL (T.unpack url)
 
 parseEntry :: [Tag Text]
-      -> Entry
+      -> Maybe Entry
 parseEntry tags = 
-  Entry (scientist tags) 
-        (graduationInfo tags)
-        (advisors tags)
+    let msc = scientist tags in
+    case msc of
+      Nothing -> Nothing
+      Just sc -> Just $
+        Entry sc (graduationInfo tags) (advisors tags)
 
-scientist :: [Tag Text] -> Text
+scientist :: [Tag Text] -> Maybe Text
 scientist tags = 
-  let TagText sc = removeClutter $ head $ tail $ head $ sections (~== "<h2 style") tags in
-  decodeUtf8 $ B.pack $ T.unpack sc 
+    let t = removeClutter <$> do 
+                 r <- headMay (sections (~== "<h2 style") tags)
+                 r2 <- tailMay r
+                 headMay r2
+--  let TagText sc = removeClutter $ headMay 
+--                                 $ tailMay 
+--                                 $ headMay 
+--                                 $ sections (~== "<h2 style") tags in
+--
+    in
+    case t of
+        Just (TagText sc) -> Just $ decodeUtf8 $ B.pack $ T.unpack sc 
+        Nothing -> Nothing  
  
 
 graduationInfo :: [Tag Text] -> Maybe GraduationInfo
diff --git a/Main.hs b/Main.hs
--- a/Main.hs
+++ b/Main.hs
@@ -70,16 +70,18 @@
   , keepDotFile  = False 
 --  , graphvizArgs = " -Tpdf -Gcharset=utf8 " &= typ "<graphviz parameters>" &= opt " -Tpdf -Gcharset=utf8 "
   , graphvizArgs = " -Gcharset=utf8 " &= typ "<graphviz parameters>" -- &= opt " -Gcharset=utf8 "
-  , onlyDotFile  = False &= help "Only create .dot file"
+  , onlyDotFile  = False &= help "Only create the GraphViz '.dot' file"
   , verbose      = False &= help "Print data to terminal."
   , includeTheses= False &= help "Include PhD thesis in output"
-  , outputFile   = enum [ FilePDF &= help "create PDF file"
+  , outputFile   = enum [ FilePDF &= help "create PDF file (default)"
                         , FilePNG &= help "create PNG file"
                         , FileSVG &= help "create SVG file"
                         ]
-  } &= summary "Mathematics Genealogy Visualizer" 
-    &= details[ "Run the program with a start-URL, for example:",
-             "# mathgenealogy http://genealogy.math.ndsu.nodak.edu/id.php?id=18231"]
+  } &= summary "Mathematics Genealogy Visualizer (C) 2010-2012 Peter Robinson thaldyron@gmail.com" 
+    &= details[ "Run the program with a start-URL, for example:"
+              ,"# mathgenealogy http://genealogy.math.ndsu.nodak.edu/id.php?id=18231"
+              ,"This program is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.  See the GNU General Public License (version 2) for more details."
+              ]
 
 -- | GraphViz style attributes for edges and nodes.
 -- See: http://hackage.haskell.org/packages/archive/graphviz/2999.12.0.4/doc/html/Data-GraphViz-Attributes.html
@@ -106,7 +108,7 @@
 
   gvExecutable <- (do m <- findExecutable "dot" 
                       if m == Nothing 
-                        then throw (userError "Error - Couldn't find 'dot' program. Did you install graphviz?")
+                        then throw $ userError "Error - Couldn't find 'dot' program. Did you install graphviz?"
                         else return (fromJust m))
 
   let traverseEntries :: [Text] -> IO [Entry]
@@ -118,10 +120,10 @@
                  `liftM` downloadEntry url
             threadDelay 1000000
             if verbose args 
-              then print e
-              else do 
-                putStr $ show c ++ " "
-                hFlush stdout
+                then print e
+                else do 
+                    putStr $ show c ++ " "
+                    hFlush stdout
             let newUrls = urlAdvisors e
             traverseEntries' (c+1) (e:acc) (url:prevUrls) 
                              ((newUrls L.\\ prevUrls) ++ urls)
@@ -158,5 +160,9 @@
 
     
 downloadEntry :: Text -> IO Entry
-downloadEntry = liftM parseEntry . getTags 
+downloadEntry t = do 
+    res <- parseEntry <$> getTags t
+    case res of
+        Nothing -> throw $ userError "Error parsing fetched data. Did you provide a valid URL to an existing math-genealogy entry?"
+        Just r -> return r
 
diff --git a/mathgenealogy.cabal b/mathgenealogy.cabal
--- a/mathgenealogy.cabal
+++ b/mathgenealogy.cabal
@@ -1,6 +1,6 @@
 Name:                mathgenealogy
 
-Version:             1.1.0
+Version:             1.1.1
 
 Synopsis:            Discover your (academic) ancestors!
 
@@ -21,8 +21,10 @@
   .
   for more options. Requires GraphViz (in particular the /dot/ program) to run.
   . 
-  /Changes in 1.1.0:/
+  /Changes in 1.1.1:/
   .
+  * provide error message when given invalid start URL
+  . 
   * documentation and code cleanup
   .
   /Changes in 1.0.0:/
@@ -73,6 +75,7 @@
                    , containers >= 0.4 && <0.6
                    , tagsoup >= 0.12.6 && <0.13
                    , HTTP >= 4000.1.2 && <5000
+                   , safe >= 0.3.3 && <0.5
       Main-Is: Main.hs
       Other-modules: Graph
                    , Extract