(like medical or technical terms) for these three languages?
If you cannot find a single trilingual file that meets your needs, you can use these official bilingual PDFs from the NSW Department of Education together: English-Vietnamese Bilingual Dictionary PDF English-Chinese Bilingual Dictionary PDF english vietnamese chinese trilingual dictionary pdf link
Pay attention to the Chinese characters (Hanzi) alongside Vietnamese; roughly 30% to 60% (like medical or technical terms) for these three languages
Remember: The best dictionary is the one you actually use. Even a 2,000-word PDF is infinitely better than a 100,000-word book that remains unopened. Start with a small glossary, learn the common Sino-Vietnamese roots, and the linguistic world of the Dragon (China) and the Phoenix (Vietnam) will open up to you through the bridge of English. learn the common Sino-Vietnamese roots