Infrared optical properties of spinels - A study of the carrier of the 13, 17 and 32 μm emission features observed in ISO-SWS spectra of oxygen-rich AGB starsD. Fabian, Th. Posch, H. Mutschke, F. Kerschbaum and J. DorschnerA&A, 373 3 (2001) 1125-1138DOI: https://doi.org/10.1051/0004-6361:20010657