A colleague has asked me to identify  the following  quote by Milton
Friedman: 
 
"Government has three primary functions: it should provide for the
military defense of the nation.  It should enforce contracts between
individuals.  And it should protect citizens against crimes against
themselves or their property."

 
She has  searched in Capitalism and Freedom, and Free to Choose, but
neither of these books contain the quote.   Does anyone know where it
comes from?
 
Thanks, 
 
Dave Colander