Chemical evolution in the early phases of massive star formation. I T. Gerner, H. Beuther, D. Semenov, H. Linz, T. Vasyunina, S. Bihr, Y. L. Shirley and Th. Henning A&A, 563 (2014) A97 Published online: 17 March 2014 DOI: 10.1051/0004-6361/201322541