 Here are the links to Hubble sites, white papers, and other locations where I found the information contained in this 2019 review. These are also the places where you can go to begin your own research. Also, thanks to Jonathan Onsted, there is a How Far Away Is It Wiki available for anyone who wants to engage in conversations about this or any channel video. I want to call your attention to a new free online textbook called Astronomy that anyone interested in astronomy can use. It is supported by the OpenStacks, a Rice University 501C3 nonprofit charity. The book builds student understanding through the use of relevant analogies, clear and non-technical explanations, and rich illustrations. I used it. Take a look at Syncrotron Radiation on page 972. And don't forget, every video has a document on the HowFarAwayIsIt.com website containing all the text. Download and translate as needed. Thanks for watching.