Over on AUTOCAT there has been discussion about form and genre headings, what to use since LC doesn't have any 155 authority records. There have been suggestions about GSAFD, AAT, using LC subject headings as the form heading also. A new, to me anyway, list of terms was the MESH Publication Types. A few of the terms are strictly medical but most have a much wider audience. There are scope notes and references, but no MARC records, as far as I could see. Have to roll your own there.