diff --git a/README.md b/README.md
index da27cdf..3532e24 100644
--- a/README.md
+++ b/README.md
@@ -61,9 +61,9 @@ information for A, N and x and press "check given output".
 - [X] Calculation of finite basis of output set (since 0.5)
 - [X] Norm preferences (since 0.6)
 
-Current version: 0.6
+Current version: 0.7
 
-Last update: 
+Last update: Improved formula simplification (using unit propagation/rewriting).
 
 ## License
 
@@ -73,5 +73,7 @@ and uses third party libraries that are distributed under their own terms (see L
 ## References
 
 [1] Makinson, D., van der Torre, L.W.N.: Input/Output Logics. J. Philosophical Logic 29(4), 383–408 (2000). https://doi.org/10.1023/A:1004748624537
+
 [2] Makinson, D., van der Torre, L.W.N.: Constraints for Input/Output Logics. J. Philos. Log. 30(2): 155-185 (2001). https://doi.org/10.1023/A:1017599526096
 
+[3] Alexander Steen, Goal-Directed Decision Procedures for Input/Output Logics. In 15th International Conference on Deontic Logic and Normative Systems (DEON 2020/2021, Munich), Fenrong Liu, Alessandra Marra, Paul Portner, and Frederik Van De Putte (Eds.), College Publications, London, 2021. (to appear). See: http://www.collegepublications.co.uk/DEON/?00003
diff --git a/about.html b/about.html
index af72a35..9b49c1a 100644
--- a/about.html
+++ b/about.html
@@ -111,7 +111,7 @@ <h2 class="h4">Development/Version</h2>
             ready-to-use for conducting own experiments without any major installation or set-up.
           </p>
           <p>
-            Current version: 0.6, see the <a href="https://github.com/I-O-Logic/iol-workbench">GitHub</a>
+            Current version: see the <a href="https://github.com/I-O-Logic/iol-workbench">GitHub</a>
             project for more details. 
           </p>
           <h2 class="h4">License</h2>
@@ -124,6 +124,7 @@ <h2 class="h4">References</h2>
           <dl>
           <dd>[1] Makinson, D., van der Torre, L.W.N.: Input/Output Logics. J. Philosophical Logic 29(4), 383–408 (2000). https://doi.org/10.1023/A:1004748624537</dd>
           <dd>[2] Makinson, D., van der Torre, L.W.N.: Constraints for Input/Output Logics. J. Philos. Log. 30(2): 155-185 (2001). https://doi.org/10.1023/A:1017599526096</dd>
+          <dd>[3] A. Steen, Goal-Directed Decision Procedures for Input/Output Logics. In 15th International Conference on Deontic Logic and Normative Systems (DEON 2020/2021, Munich), Fenrong Liu, Alessandra Marra, Paul Portner, and Frederik Van De Putte (Eds.), College Publications, London, 2021. (to appear). See: http://www.collegepublications.co.uk/DEON/?00003</dd>
           </dl>
         </div>
       </div>
diff --git a/index.html b/index.html
index b073581..8884622 100644
--- a/index.html
+++ b/index.html
@@ -46,7 +46,7 @@
       <div class="row">
         <div class="col-sm text-center">
           <div class="float-right h2 ml-0">
-            <span class="text-muted mr-2" style="font-size:small">Version 0.6</span>
+            <span class="text-muted mr-2" style="font-size:small">Version 0.7</span>
             <a href="about.html"><span style="font-size:medium;font-variant:small-caps">About</span></a>
           </div>
           <h1 class="h2" style="font-variant:small-caps">I/O Logics Workbench</h1>