https://ntrs.nasa.gov/citations/19930009973
A strong 3.4 micron emission feature in comet Austin 1989c1 - NASA Technical Reports Server (NTRS)
High resolution 2.8-4.0 micron spectra of the 'new' comet Austin 1989c1, taken on 15-16 May 1990 confirm the presence of the broad emission features around 3.4...