use Date::Calc qw ( Monday_of_Week Add_Delta_Days );

sub weekToDays {
    $week = shift;
    $year = shift;

    ($year,$month,$day) = Monday_of_Week($week,$year);

    ($y, $m, $d) = Add_Delta_Days( Monday_of_Week( $week, $year ), 6);

    return "$day/$month/$year to $d/$m/$y";
}

print "First week of 2013: ".weekToDays ( 1, 2013) ."\n" ;

print "Second week of 2013: ".weekToDays ( 2, 2013) ."\n" ;