diff --git a/docs/source/tutorial.rst b/docs/source/tutorial.rst
index 373184a..7b1cf2e 100644
--- a/docs/source/tutorial.rst
+++ b/docs/source/tutorial.rst
@@ -4,7 +4,7 @@
 =======
 
 The ndnSIM 2.0 is NS-3 module that implements Named Data Networking (NDN) communication
-model, the clean slate Internet design. 
+model, the clean slate Internet design.
 
 We invite you to `join our mailing list
 <http://www.lists.cs.ucla.edu/mailman/listinfo/ndnsim>`_ to see and participate in
@@ -44,10 +44,14 @@
 
 If you refer to ndnSIM in a published work, please cite the following papers, not just the ndnSIM website. Thank you!
 
+**For ndnSIM >= 2.0:**
+
 - **S. Mastorakis, A. Afanasyev, and L. Zhang, "On the Evolution of ndnSIM: an Open-Source Simulator for NDN Experimentation," ACM SIGCOMM Computer Communication Review (CCR), July 2017** (`PDF <https://ccronline.sigcomm.org/wp-content/uploads/2017/08/sigcomm-ccr-final112-full-letter.pdf>`__, `BibTex <http://web.cs.ucla.edu/~mastorakis/bibtex-ndnsim>`__)
 
 - **S. Mastorakis, A. Afanasyev, I. Moiseenko, and L. Zhang, "ndnSIM 2: An updated NDN simulator for NS-3," NDN, Technical Report NDN-0028, Revision 2, 2016** (`PDF <https://named-data.net/wp-content/uploads/2016/11/ndn-0028-2-ndnsim-v2.pdf>`__, `BibTex <http://lasr.cs.ucla.edu/afanasyev/bibwiki/bibtex/399>`__)
 
+**For ndnSIM 1.0:**
+
 - **A. Afanasyev, I. Moiseenko, and L. Zhang, "ndnSIM: NDN simulator for NS-3," NDN, Technical Report NDN-0005, 2012** (`PDF <https://named-data.net/wp-content/uploads/TRndnsim.pdf>`__, `BibTex <http://lasr.cs.ucla.edu/afanasyev/bibwiki/bibtex/367>`__)
 
 .. * :ref:`search`