Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thanh va » thanh van, hanh va, thanh ha
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
van cau » van dau, van hau, van chat
truc va » thuc va, trung va
cua tre » cua te, cuu tre, cua triet

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: su sach ky tang xa hoi. hieu van cau ((truc va) OR (thuc vat)) thanh va ((cua tre) OR (cua vat))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky tang xa hoi. hieu van cau ((truc va) OR (thuc vat)) thanh va ((cua tre) or (cua vat))~".
• Adding a wildcard symbol may retrieve word variants: su sach ky tang xa hoi. hieu van cau ((truc va) OR (thuc vat)) thanh va ((cua tre) or (cua vat))*.