--- a/filter/ob_grep.xml	Fri May 31 22:31:31 2013 +0200
+++ b/filter/ob_grep.xml	Sat Jun 01 20:02:50 2013 +0200
@@ -53,6 +53,11 @@
 **What it does**
 
 The obgrep tool can be used to search for molecules inside multi-molecule database files (e.g., SMILES, SDF, etc.) or across multiple files.
+It is known that not all SMARTS features from the Daylight Toolkit are supported, please have a look here_.
+
+
+.. _obgrep: http://openbabel.org/wiki/Obgrep
+.. _here: http://openbabel.org/wiki/SMARTS
 
 -----
 
@@ -61,8 +66,10 @@
 
 **References**
 
-Rajarshi Guha, Michael T. Howard, Geoffrey R. Hutchison, Peter Murray-Rust, Henry Rzepa, Christoph Steinbeck, Joerg Kurt Wegner, Egon Willighagen. "The Blue Obelisk -- Interoperability in Chemical Informatics." J. Chem. Inf. Model. (2006) 46(3) 991-998. DOI:10.1021/ci050400b
+N M O'Boyle, M Banck, C A James, C Morley, T Vandermeersch, and G R Hutchison. "Open Babel: An open chemical toolbox." J. Cheminf. (2011), 3, 33. `DOI:10.1186/1758-2946-3-33`_
 The Open Babel Package http://openbabel.sourceforge.net/
 
+.. _DOI:10.1186/1758-2946-3-33: http://www.jcheminf.com/content/3/1/33
+
     </help>
 </tool>