This list is designed for a technology leader. I'm going to assume that the person who is looking at this is technical enough to know what a database is and roughly how the internet works, but will be less technical than other reading lists that are out there.
So, to begin, the first thing you need is a picture. Words are great and important and you can't understand distributed ledger or blockchain technology without words. But it is also important to have a picture in your mind, so you can refer to it later.
Here is the best picture I have found describing bitcoin specifically:
Here is a good picture for distributed ledger more generally:
Here are some overviews, the first one is expressing the distinction between distributed ledger and blockchain:
This is from IBM and introduces HyperLedger, which is a Linux Foundation Project they are supporting:
How do distributed ledgers fit into the broader world of data storage:
A really good description of the problem distributed ledgers are solving:
Do you need a distributed ledger?
I hope this is helpful. I'm going to keep adding and editing. I may make it a static page at some point.