Perhaps you should try some spelling variations:
hieu van » thien van, lieu va, hieu ve
than duc » tran duc, phan duc, than doc
van hanh » van thanh, ban hanh, van anh
su sach » so sach, vu sach
sach vu » sach va, sach tu, sach uu
vu nang » vuc nang, va nang, vu dang
cao hoi » cau hoi, co hoi, cao hoc
hieu va » lieu va, hieu qua
duc van » duc va, duc tan, duc manh
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach vu nang cao hoi. ((hieu van) or (hieu va)) than duc van hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach vu nang cao hoi. ((hieu van) OR (hieu va)) than duc van hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach vu nang cao hoi. ((hieu van) or (hieu va)) than duc van hanh di cua tre*.