globe
  1. Seeing Theory

    Website  Click on Units at the top of the page to access a variety of visualisation resources.

  2. An Introduction to Mathematical Statistics and Its Applications - Richard J. Larsen, Morris L. Marx 2010

    Book  Chapter 11 on Regression is useful. In particular pages 558-562 of physical copy (or 582-586 of the digital copy of this book)

  3. Introduction to mathematical statistics - Robert V. Hogg, Joseph W. McKean, Allen T. Craig 2014 (electronic resource)

    Book 

  4. Mathematical Statistics and Data Analysis - John Rice 2013

    Book  earlier editions would be generally appropriate for the mathematical statistics aspect