Over the years I have looked for various repositories of information that can be downloaded and read in situations where (a) I do not have internet access and (b) I really want to figure out how to do certain things.
I love paper books so do not get me wrong but they are prone to water damage, mold, are heavy to carry around and they also require having the space to store them.
So this lead me many years ago to try to find a solution and I basically downloaded every free pdf and text document I could find or alternatively I would use the 'print to pdf' function to copy web pages.
All of which definitely works but then it required a lot of tedious sorting, grouping, labeling and sometimes renaming of the digital media that I was hoarding.
Needless to say it eventually grew into a tiresome project and then one day I learned about the CD3WD project which was an amazing discovery for me in and of itself because it was an existing repository of information that was well sorted, easy to download and covers many of the topics that I was interested in learning about or needing to reference to move my own projects forward.
Although it has changed and grown over the years the project itself has persisted and is still a 'must have' (in my not so humble opinion) for anyone in need of free reference material but lacks easy access to information online. In other words it is well worth having a copy of it safely stored on a hard drive, thumb drive or SD card that can be used in situations where connectivity to the outside world is limited or nonexistent.
The Wikipedia page about it is well worth the read for understanding the project's scope and it's history. It also has the links to where it can be downloaded from in both direct download form, Zip form and torrent form and where it can be read online. I am including a link to it here: https://en.wikipedia.org/wiki/CD3WD
The online version of CD3WD is now defunct as of 2020 and must be viewed via Web Archive found here: https://web.archive.org/web/20151128180543/http://www.fastonline.org/CD3WD_40/CD3WD/INDEX.HTM
That is all. Good Luck!