The supernova remnant W44: Confirmations and challenges for cosmic-ray acceleration M. Cardillo, M. Tavani, A. Giuliani, S. Yoshiike, H. Sano, T. Fukuda, Y. Fukui, G. Castelletti and G. Dubner A&A, 565 (2014) A74 Published online: 14 May 2014 DOI: 10.1051/0004-6361/201322685