Probability and Statistics Cookbook by Matthias Vallentin.
From the webpage:
The cookbook contains a succinct representation of various topics in probability theory and statistics. It provides a comprehensive reference reduced to the mathematical essence, rather than aiming for elaborate explanations.
Very summary presentation so better as a quick reminder type resource.
I was particularly impressed by the univariate distribution relationships map on the last page.
In that regard, you may want to look at John D. Cook’s Diagram of distribution relationships
and the links therein.