1. Chevalier, R.A. 1980, Astrophys. Letters 21, 57.
2. Erickson, N.R., Davis, J.H., Evans II, N.J., Loren, R.B., Mundy, L., Peters III, W.L., Scholtes, M. and Vanden Bout, P.A. 1980, I.A.U. 87, “Interstellar Molecules”, ed. B.H. Andrew ( Boston, D. Reidel ) 25.
3. Goldsmith, P.F., Erickson, N.R., Fetterman, H.R., Clifton, B.J., Peck, D.D., Tannenwald, P.E., Koepf, G.A., Buhl, D and McAvoy, N. 1981, Ap. J. (Letters) 243, L79.
4. Graedel, T.E., Frerking, M.A. and Langer, W.D. 1981 preprint.
5. Hollenbach, D.J., 1980, in I.A.U. 87, “Interstellar Molecules”, ed. B.H. Andrew ( Boston, D. Reidel ) 445.