34th session was on Mixnets as lots of people suggested in the past. As a preparation we read the Loopix paper.
Piotrowska, Ania M., et al. “The loopix anonymity system.” 26th {USENIX} Security Symposium ({USENIX} Security 17). 2017.
https://www.usenix.org/system/files/conference/usenixsecurity17/sec17-piotrowska.pdf
The corresponding talk by Ania Piotrowska is very much worth watching as an additional resource.