Perhaps you should try some spelling variations:
thien hach » thien thanh, hien hanh
thanh tung » thanh cong
nhung cong » dung cong, thong cong, hang cong
hieu cach » hieu cac, chieu sach, hieu ca
cua nhung » va nhung
tung cua » trung cua, tuong cua, dung cua
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 hach)) - thanh tung 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 hach)) - thanh tung cua nhung cong ((dan toan) OR (van tan)) tap.
• Adding a wildcard symbol may retrieve word variants: hoc ((hieu cach) or (thien hach)) - thanh tung cua nhung cong ((dan toan) or (van tan)) tap*.