The massive stellar population of W49: A spectroscopic survey Shi-Wei Wu, Arjan Bik, Joachim M. Bestenlehner, Thomas Henning, Anna Pasquali, Wolfgang Brandner and Andrea Stolte A&A, 589 (2016) A16 Published online: 06 April 2016 DOI: 10.1051/0004-6361/201527823