Wave equation migration: two approaches

This paper introduces the notion of an anticipation component to scientific publishing in that it references work done after it was written in 1976. The reason is that in those far-off pre-word-processor days in the early dawn of the junk mail era, we were both somewhat dilatory about writing anything up and the paper led a ghostly existence as an Offshore Technology Conference preprint in the twilight zone somewhere between the spoken and the published word.