Henry Hazlitt wrote Economics in One Lesson in six weeks in early 1946. He was on a tight deadline: a leave of absence from The New York Times. He did not include footnotes.
In 1946, there were few materials to footnote. Hazlitt stood alone in the community of financial journalists.
Today, there is a wealth of material available online to defend every one of his chapters.
I have gone back and added a link to every chapter. Each link goes to a page on GaryNorth.com. On each page are links to support materials. There are even videos. Here is an example.
The book is now suitable as a homeschool course textbook in Christian economics.
Click the link.