$one;
$two;
$link = [$first = &$one, $second = &$two];
$link[0] = 1;
$link[1] = 2;
echo $one; // не выводит 1
echo $two; // не выводит 2
$link = [&$one, &$two];
$one = 3;
$two = 4;
$link = [0 => &$one, 1 => &$two];
$link[0] = 1;
$link[1] = 2;
echo $one."\n";
echo $two."\n";