Perhaps you should try some spelling variations:
hieu tinh » chieu tinh, lieu tinh, kieu tinh
vuong tac » tuong tac, vuong tat, huong tac
doc hieu » toc thieu, hoc thieu, hoc hien
tram van » tam van, trang van, tranh van
tran van » luan van
tac phan » tac pham, tai phan, tac phat
phan tap » phan lap, han tap, pha tap

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: doc hieu tinh - hanh ((tram van) or (tran van)) hoang vuong tac phan tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc hieu tinh - hanh ((tram van) OR (tran van)) hoang vuong tac phan tap.
• Adding a wildcard symbol may retrieve word variants: doc hieu tinh - hanh ((tram van) or (tran van)) hoang vuong tac phan tap*.