added reference

rrspec.m

@@ -18,6 +18,10 @@ function varargout = rrspec(varargin)
 %
 %    See also TAUCRP, RTSPEC.
 %    
+%    References: 
+%    Zbilut, J. P., Marwan, N.: 
+%    The Wiener-Khinchin theorem and recurrence quantification, 
+%    Phys. Lett. A, 372, 2008.
 
 % Copyright (c) 2008-2009
 % Norbert Marwan, Potsdam Institute for Climate Impact Research, Germany
@@ -31,6 +35,9 @@ function varargout = rrspec(varargin)
 % $Revision$
 %
 % $Log$
+% Revision 5.2  2009/03/24 08:36:24  marwan
+% correction of frequency scale
+%
 % Revision 5.1  2008/07/02 12:01:13  marwan
 % initial import
 %