This is a free program that will allow you to download complete copies of websites. You can also download SiteSucker from the website at ricks-apps.com/osx/sitesucker/index.html. If you download the app from the website, double-click the downloaded DMG file. Drag the SiteSucker application icon to your Applications folder to install it. With SiteSucker's default settings, every page on the website will be copied and downloaded to your computer. SiteSucker will follow every link it finds but will only download files from the same web server.  Advanced users can adjust the settings for SiteSucker, but if you just want to copy a website you don't need to worry about changing anything. SiteSucker will copy the complete website by default. One setting that you may want to change is the location for the copied website on your computer. Click the Gear button to open the Settings menu. In the "General" section, use the "Destination" menu to select where you want the files to be saved. SiteSucker will start downloading all of the content from the website that you entered into the URL field. This can potentially take a very long time, and you can monitor the progress in the bottom part of the SiteSucker window. If you're trying to download content from a password protected site, you'll be prompted for your login information. By default, SiteSucker will check your Keychain first to see if your login information is already stored. If it isn't, you'll need to enter this information manually. Once you have finished downloading the site, you can view it offline just as if you were online. SiteSucker will localize the web pages so that they point to the local downloaded files instead of the original online address. This allows you to view the entire site without an internet connection.

TL;DR in Vietnamese:
Tải SiteSucker từ kho ứng dụng Mac App Store. Nhập URL trang web mà bạn muốn sao chép. Nhấp vào nút "Download" (Tải) để bắt đầu lưu trang web. Gõ tên người dùng và mật khẩu nếu được nhắc. Xem trang web sao chép sau khi hoàn tất.