#36 is part of #33, but while I've read #36, I haven't read all the books in the Chronicles. They probably singled out Wardrobe because that's usually the one everyone's read.

You should give Mockingbird a try. I always said I'd get around to it but never did. And then I finally had my hands on a copy, and gave it a try. Let's just say that it's a shame Harper Lee only wrote the one book!