Let me know if: You're getting a "Verification Error" when adding the URL. The repo appears empty after you add it.
Essential Cydia Sources for iPhone | PDF | Mobile Phones - Scribd
Verification is a crucial process that ensures the authenticity and safety of a Cydia repository. A verified repository guarantees that the packages and tweaks hosted within are thoroughly tested, secure, and free from malware. By verifying the VN Repo, users can trust that the packages they install are reliable and won't harm their devices.
If you want to add the official source, here is the URL you will find referenced across most legitimate jailbreak communities:
: Unlike official app stores, there is no central authority that "verifies" repos. "Verified" is often used colloquially by users to mean a repo is currently online, safe from malware, and contains functional packages. Current Status and Safety
It is important to note that the official (which handled payments) shut down in late 2018. Consequently, no third-party repo is "verified" in a commercial sense anymore. Most modern "verified" repos are now hosted on GitHub Pages or via dedicated developer sites. Modern Alternatives for Vietnamese Users