https://docs.google.com/presentation/d/18ACI3xJXV1D_chKubhXIBBekZwIr-6_0ixtm4xQvKMo/edit#slide=id.g2a6801f8034_0_134

https://medium.com/stakefish/proof-of-stake-a-brief-history-4baa3effc917

https://medium.com/stakefish/beginners-guide-to-ethereum-2-0-24fe728a8501

https://medium.com/stakefish/deeper-dive-into-ethereum-2-0-part-2-90500eb06743

https://medium.com/stakefish/deeper-dive-into-ethereum-2-0-part-1-93c475a18735