You can just use a website mirroring tool like wget, they've been around for ages. I've done just that with plenty of reference websites.

Don't forget to set an acceptable delay to ensure you don't overload the servers, though. Mine usually run all night.

Selenium's webdriver is great for this, they have different implementations so you can use it like wget (but more sophisticated) where it doesn't run an actual browser or you can have it run an implementation where it actually runs a browser, like Chrome or Firefox (good for debugging)