Perhaps you should try some spelling variations:
van hieu » cao hieu
vanh dai » van dai, vanh tai, lanh dao
vu sach » vu bach, su sach, vu khach
ky tang » ky nang, ky dang, kho tang
van hoc » van hoa
hieu ve » hieu va, hieu van
va vanh » va van, va danh, va hanh
cua tre » cua te, cuu tre, cua triet
vu sac » vu san, va sac, vu cac
ve dat » de dat, va dat, ve dao
nuoc » quoc, duoc, ngoc

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((vu sac) OR (vu sach)) ky tang ((van hieu) or (van hoc)). hieu ve dat nuoc va vanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((vu sac) OR (vu sach)) ky tang ((van hieu) OR (van hoc)). hieu ve dat nuoc va vanh dai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((vu sac) OR (vu sach)) ky tang ((van hieu) or (van hoc)). hieu ve dat nuoc va vanh dai cua tre*".