Brief Announcement: Why Extension-Based Proofs Fail
D.-A. Alistarh, J. Aspnes, F. Ellen, R. Gelashvili, L. Zhu, in:, Proceedings of the 39th Symposium on Principles of Distributed Computing, Association for Computing Machinery, 2020, pp. 54–56.

Long-lived snapshots with polylogarithmic amortized step complexity
M.A. Baig, D. Hendler, A. Milani, C. Travers, in:, Proceedings of the 39th Symposium on Principles of Distributed Computing, Association for Computing Machinery, 2020, pp. 31–40.