diff --git a/doc/bib.bib b/doc/bib.bib
index 0e07a0b..bb3a3ac 100644
--- a/doc/bib.bib
+++ b/doc/bib.bib
@@ -34,7 +34,7 @@
 	Author="Brian W. Kernighan",
 	Title="{PIC}---A Graphics Language for typesetting: Revised User Manual",
 	Type="Computer Science Technical Report",
-	Note="Available online at http://cm.bell-labs.com/cm/cs/cstr",
+	Note="Available online at \url{http://cm.bell-labs.com/cm/cs/cstr}",
 	Number="116",
 	Month=dec,
 	Year="1984",
@@ -70,3 +70,14 @@
 	ISBN="0-201-30998-X",
 	Where="dds-CD1"
 	}
+
+@Book	{Spi06,
+	Author="Diomidis Spinellis",
+	Title="Code Quality: The Open Source Perspective",
+	Publisher="Addison-Wesley",
+	Address="Boston, MA",
+	URL="http://www.spinellis.gr/codequality",
+	XISBN="0-321-16607-8",
+	Year=2006
+	}
+