diff --git a/src/spicelib/devices/jfet2/jfet2temp.c b/src/spicelib/devices/jfet2/jfet2temp.c
index 8f6014361..eee92cabd 100644
--- a/src/spicelib/devices/jfet2/jfet2temp.c
+++ b/src/spicelib/devices/jfet2/jfet2temp.c
@@ -3,7 +3,8 @@ Base on jfettemp.c
 Copyright 1990 Regents of the University of California.  All rights reserved.
 Author: 1985 Thomas L. Quarles
 
-Modified to add PS model and new parameter definitions ( Anthony E. Parker )
+Modified to add PS model and new parameter definitions ( Anthony E. Parker ).
+See http://ngspice.sourceforge.net/external-documents/models/psfet.pdf
    Copyright 1994  Macquarie University, Sydney Australia.
    10 Feb 1994: Call to PSinstanceinit() added
                 Change gatePotential to phi and used rs and rd for