@misc{cryptoeprint:2016:1048,
    author = {Juan A. Garay and Aggelos Kiayias and Nikos Leonardos},
    title = {The Bitcoin Backbone Protocol with Chains of Variable Difficulty},
    howpublished = {Cryptology ePrint Archive, Report 2016/1048},
    year = {2016},
    url = {https://eprint.iacr.org/2016/1048},
}