$re = '/\b[^.]+\([^()]+\b(\d{2}|\d{4})\s*\)[^.]*\./m';
$str = 'Abc def ghi (foo 2015).
Trondheim is a small city with a university and 140000 inhabitants. Its central bus systems has 42 bus lines, serving 590 stations, with 1900 (departures per) day in average. T h a t gives approximately 60000 scheduled bus station passings per day, which is somehow represented in the route data base. The starting point is to automate the function (Garry Weber, 2005) of a route information agent.
Abc def ghi (foo 2015).
Abc def ghi (foo 201).';
preg_match_all($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