The Warden of the Tomb is an expressionist play fragment by Kafka. Although incomplete, possibly extremely so, it's still decently long - about fourteen pages. Sadly (to me at least), as far as I can tell it has received little attention: basically the only writing in English I can find on it are a paper of Burç İdem Dinçel and a (medical!) paper of Mishara. Even in German there seems to be little written on it, with the only example I can find being a paper by Meinel (although since I can't read German it's quite possible I've missed many).
However, I'm not particularly familiar with the field so my "literature search" has been essentially limited to just googling, and I'm well aware that there could be lots of great sources on the topic which aren't so easy to find.
I'm interested in whether there are other sources at least partially focusing on Warden. To avoid asking for a list of references, I'll phrase my question as:
Is there "reasonably serious" secondary literature at least partially focusing on Warden other than the papers mentioned above? Failing that, where are places I might look for such literature?
I'm especially, although not exclusively, interested in sources in English (sadly, that's the only language I can read).