FREE PDF BOOK HEATHKIT A guide to the Amateur Radio and SWL Products by WA7ZZE

 http://w8dyy.org/wp/wp-content/uploads/2017/11/Heathkit-AGuideToTheAmateurRadioProducts.pdf

You can buy this one

https://wa7zze.com/amateur-radio

http://heathkit.free.fr/

https://people.ohio.edu/postr/bapix/HLegacy.htm