Silicate features in Galactic and extragalactic post-AGB discs C. Gielen, J. Bouwman, H. Van Winckel, T. Lloyd Evans, P. M. Woods, F. Kemper, M. Marengo, M. Meixner, G. C. Sloan and A. G. G. M. Tielens A&A, 533 (2011) A99 Published online: 07 September 2011 DOI: 10.1051/0004-6361/201117364