$re = '/(?<=\[\[).*(?=\]\])/m';
$str = ': [[Bertus Aafjes]] (1914–1993), NL
: [[Jeppe Aakjær]] (1866–1930), DK
: [[Johannes Aal]] (um 1500–1551), CH
: [[Hans Aanrud]] (1863–1953), NO
: [[Emil Aarestrup]] (1800–1856), DK
: [[Soazig Aaron]] (* 1949), FR
: [[Ivar Aasen]] (1813–1896), NO';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php