Perhaps you should try some spelling variations:
thien thanh » tien thanh, thi thanh, hien hanh
thanh trung » thanh tung
nhung cong » dung cong, thong cong, hang cong
hieu cach » hieu cac, chieu sach, hieu ca
trung cua » truong cua, trung tuan, trung cap
cua nhung » va nhung
dan toan » van toan, dan than, manh toan
van tan » van tuan, van ban, van tai

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc ((hieu cach) or (thien thanh)) - thanh trung cua nhung cong ((dan toan) or (van tan)) tap~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((hieu cach) OR (thien thanh)) - thanh trung cua nhung cong ((dan toan) OR (van tan)) tap.
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu cach) or (thien thanh)) - thanh trung cua nhung cong ((dan toan) or (van tan)) tap*.