Hi!
Her is some more stuff. With this and your own reading about date and time manipulation you should be able to figure out this.
$start = strtotime('2006-01-29 00:00:00');
$dayNumbOfWeek = date('w', $start);
// 1 = monday
if($dayNumbOfWeek != 1)
$mondayInStartWeek = strtotime("last Monday", $start);
else
$mondayInStartWeek = $start;
$saturdayInStartWeek = strtotime("next Saturday", $mondayInStartWeek);
$sundayInStartWeek = strtotime("+1 day", $saturdayInStartWeek);
$yearOnMonday = strftime('%Y', $mondayInStartWeek);
$yearOnSunday = strftime('%Y', $sundayInStartWeek);