First method: Here is the easiest way to download an individual book. From the main page of this web site, place your mouse curser on the the link to the book you want to download. Right-click your mouse. Then choose "Save As" or "Save Target As" from the menu that pops up and select the folder to which you want to save the book.
Second method: Books 1-79 can also be downloaded in one large ZIP archive file. First download lesbooks.exe into a folder by itself. Once it is downloaded, execute the file. This will make it extract all of the books and diagrams into the folder that you choose. Then, you can run "index.html" with your web browser when you are off-line. It may try to connect to the internet. If so, just close the window instead of logging in. All the links to books on this site should then work off-line. Of course the audios will not work off-line unless you download them individually using the first method. The same is true for some of the other miscelaneous links. For those files, you will need to get on-line. Let me know if you have problems getting the download to work.