$re = '/^(?:\d+\. )([^:,]*,[^:,]*)(?=[:,])/m';
$str = '144. Spalding, K.L., Buchholz, B.A., Bergman, L.E., Druid, H., Frisén, J.: Forensics: e age written in teeth by nuclear tests. Nature 437(7057) (2005) 333–334
145. Lovecraft, H.P.: HP Lovecraft: Tales: Tales. Library of America (2005)
146. Duncan, R.: A survey of parallel computer architectures. Computer 23(2) (1990) 5–16
147. Santos, N., Hoshino, Y.: Global distribution of rotavirus serotypes/genotypes and its implication for the development and implementation of an effective rotavirus vaccine. Reviews in medical virology 15(1) (2005) 29–56
148. DIARRHOEA, R.: Rotavirus and other viral diarrhoeas. Bulletin of the World Health Organization 58(2) (1980) 183–198
149. Barton, T.: Power and knowledge: astrology, physiognomics, and medicine under the Roman Empire. University of Michigan Press (2002)
150. Gauquelin, M.: The cosmic clocks: From astrology to a modern science. H. Regnery Company (1967)';
preg_match_all($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