Chemical Gradients in the Orion Molecular Cloud Ungerechts, H. ; Bergin, E. A. ; Carpenter, J. ; Goldsmith, P. F. ; Irvine, W. M. ; Lovell, A. ; McGonagle, D. ; Schloerb, F. P. ; Snell, R. L. Abstract Publication: Bulletin of the American Astronomical Society Pub Date: September 1991 Bibcode: 1991BAAS...23.1372U