1. Allamandola, L.J.: 1984, in “Galactic and Extragalactic Infrared Spectroscopy” , XVIth ESLAB Symposium, eds. M.F. Kessler, J.P. Phillips and T.D. Guyenne (Dordrecht: Reidel), p. 5.
2. Allamandola, L.J., Tielens, A.G.G.M., Barker, J.R.: 1985, Astrophys. J. (Letters) 290, L25.
3. Blanco, A., Borghesi, A., Fonti, S., Orofino, V., Bussoletti, E., Colangeli, L.: 1988, “Experimental evidences for HAC and PAHs soup in space” ,present book.
4. Bohren, C.F., Huffmann, D.R.: 1983, “Absorption and scattering of light by small particles” ,Wiley (New York).
5. Borghesi, A., Bussoletti, E., Colangeli, L. ,Minafra, A., Rubini, F.,: 1983a, Infrared Phys. 23, 85.