General

Earlham’s Lilly Library has the ebook Data Visualization with D3.js Cookbook available for full online viewing if you’re at the college. If you’re not at the college, go through here (requires Earlham login info). The accompanying d3-cookbook is available here.
Chris Albon on Data Science and Political Science for Social Good
Common probability distributions: where they come from and which to use.
Some very nice Jupyter Notebooks on Linear Algebra.
Aggregation of data sources in various topics

Tools