Recently I picked up the book 'Ethereum: Blockchains, Digital Assets, Smart Contracts and Decentralized Autonomous Organizations'.
So far the book has been excellent at breaking down the technical aspects of blockchain and cryptocurrency technologies and explaining them in a way that anyone can understand. I really enjoy the way that Henning writes and the book is structured in such a way that it's easy to just pick up and read on a particular topic for 5 minutes without having to remember everything before it. Highly recommended to anyone interested in learning about how our beloved blockchain works under the hood :)
You can buy it on amazon: https://www.amazon.com/Ethereum-Blockchains-Decentralized-Autonomous-Organizations/dp/1523930470