Perhaps you should try some spelling variations:
doc thuc » hoc thuc, do thuc, hoc thuoc
trinh vi » trinh va, trinh ve, trinh viet
binh voi » binh hoi, minh voi, tinh voi
trong xa » trong xay, trong ca, trong xu
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
thuc va » thuc vat, thuc dan, thuc day
van doc » van duoc, van hoc, van loc
sach tu » sach thu, cach tu, sach ty
tang xa » trang xa, tang ma, lang xa
cua tre » cua te, cuu tre, cua triet

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 tu ((tang xa) or (trong xa)) hoi. hieu van doc thuc va ((binh voi) or (trinh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach tu ((tang xa) OR (trong xa)) hoi. hieu van doc thuc va ((binh voi) OR (trinh vi)) cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach tu ((tang xa) or (trong xa)) hoi. hieu van doc thuc va ((binh voi) or (trinh vi)) cua tre*.