use Date::Manip;
$weekno = 30; # want the 30th week of the year;
$day = &DateCalc("1/1/2003","+${weekno}week");
$daydiff = 7 - &UnixDate($day, "%w");
$day1 = &DateCalc($day, "+${daydiff}day");
$day2 = &DateCalc($day1, "+6day");
print "$day1, $day2\n";