May I humblely ask what is a good reference for conormal distributions (for student with some rudimentary pseudo-differential operator background)? I heard from my advisor that it is useful in index theory, but most of the lecture notes I read are quite opaque (like Simanca's) by using baroque notations, and it is difficult to see the theory in transparent manner without going over all the technical details. For a concrete example, it is not clear to me how to compute the principal symbol of the product of two conormal distributions.
I assume this is a subject well known to experts(like Richard Melrose, Rafe Mezzeo, etc), but I found it difficult to find a good reference that does not assume I know most of the basic theory already.
Update: I know Hormander's book is the Bible in our field. It is just I do not know if I will have enough time to digest it properly. Is there any alternatives?