Perhaps you should try some spelling variations:
danh viet » anh viet, ninh viet, nang viet
danh kien » dinh kien, linh kien, van kien
vu sach » vu bach, su sach, vu khach
cac duc » cac du, cao duc, cac dac
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
ky tang » ky nang, ky dang, kho tang
cuc tre » duc tre, cua tre, cuu tre
ma hoi » mai hoi, xa hoi, me hoi

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

• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky tang ((ma hoi) OR (ma hoa)). hieu va cac duc va ((danh kien) OR (danh viet)) cuc tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky tang ((ma hoi) or (ma hoa)). hieu va cac duc va ((danh kien) OR (danh viet)) cuc tre~".
• Adding a wildcard symbol may retrieve word variants: vu sach ky tang ((ma hoi) or (ma hoa)). hieu va cac duc va ((danh kien) OR (danh viet)) cuc tre*.