On the origin of the 19.5 m feature - Identifying circumstellar Mg-Fe-oxides Th. Posch, F. Kerschbaum, H. Mutschke, J. Dorschner and C. Jäger A&A, 393 1 (2002) L7-L10 Published online: 18 September 2002 DOI: 10.1051/0004-6361:20021127