diff --git a/timeline/week18.txt b/timeline/week18.txt
index 2c52f1dce701f40bb0f7c3afc3da7e134e60a0c3..be0dcb3dd93262669cd973a509052bfb300a1d98 100644
--- a/timeline/week18.txt
+++ b/timeline/week18.txt
@@ -7,22 +7,25 @@ Week 18 (27.04.-03.05.)
 
 	[~] import all data into graphdb
 
-		[x]  import coq data into graphdb
+		[x] import coq data into graphdb
 
-		     -> had to use a little scritping to remove some
-		        invalid(?!) parts from the rdf files
+		-> had to use a little scritping to remove some
+		invalid(?!) parts from the rdf files
 
-		     -> used script /ulo/coq-cut.sh
+		-> used script /ulo/coq-cut.sh
 
 		[~] import isabelle data into graphdb
 
-			-> importing the isabelle rdf files I get an error
+		-> importing the isabelle rdf files I get an error
 
-				org.eclipse.rdf4j.sail.SailException: Invalid IRI value
+			org.eclipse.rdf4j.sail.SailException: Invalid IRI value
 
-			for all files; I wonder if the proposed IRI scheme is actually
-			illegal; will have to look into that
+		   for all files; I wonder if the proposed IRI
+		   scheme is actually illegal; will have to
+		   look into that
 
+		-> RDF [1] uses IRIs which "are a generialization of URI [2]";
+		   IRIs are also defined by the IETF [3]
 
 	[ ] run all quries from ulo paper in graphdb
 
@@ -37,3 +40,7 @@ Week 18 (27.04.-03.05.)
 References
 ==========
 
+
+[1] https://www.w3.org/TR/2014/REC-rdf11-concepts-20140225/
+[2] https://tools.ietf.org/html/rfc3986
+[3] https://tools.ietf.org/html/rfc3987