DTU Risoe Campus  
A FORTRAN IV Version of the SumofExponential LeastSquares Code EXPOSUM
by Peter Kirkegaard (September 1970) 

Some Aspects of the General LeastSquares Problem for Data Fitting
by Peter Kirkegaard (August 1971)  
The LeastSquares Fitting Programme POSITRONFIT: Principles and Formulas
by Peter Kirkegaard (September 1971)  
Positron lifetimes in water and ice, and in frozen aqueous solutions
by Morten Eldrup (November 1971)  
PATFIT88: A DATAPROCESSING SYSTEM FOR POSITRON ANNIHILATION SPECTRA ON MAINFRAME AND PERSONAL COMPUTERS
by Peter Kirkegaard, Niels Jørgen Pedersen and Morten Eldrup (February 1989  revised August 1997)  
RisoeR1652 
PALSfit: A computer program for analysing positron lifetime spectra
by Peter Kirkegaard; Jens V. Olsen; Morten Eldrup; Niels Jørgen Pedersen (2009) 