$re = '/\)\.\s+([^.]+)/m';
$str = 'American Psychological Association. (2016). Center for epidemiological studies depression (CESD). Retrieved December 7, 2016, from American Psychological Association, http://www.apa.org/pi/ about/publications/caregivers/practice-settings/ assessment/tools/depression-scale.aspx
Beattie, G.S. (2005, November). Social Causes of Depression. Retrieved May 31, 2017, from http:// www.personalityresearch.org/papers/beattie.html';
preg_match_all($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