Perhaps you should try some spelling variations:
doc thuc » hoc thuc, do thuc, hoc thuoc
trinh ve » trinh he, trinh va, trinh vi
trong xa » trong xay, trong ca, trong xu
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
tinh vi » trinh vi, tinh voi, tinh va
thuc va » thuc vat, thuc dan, thuc day
van doc » van duoc, van hoc, van loc
sach ty » sach y, sach tu, sach thu
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 ty ((tang xa) or (trong xa)) hoi. hieu van doc thuc va ((tinh vi) or (trinh ve)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((tang xa) OR (trong xa)) hoi. hieu van doc thuc va ((tinh vi) OR (trinh ve)) cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach ty ((tang xa) or (trong xa)) hoi. hieu van doc thuc va ((tinh vi) or (trinh ve)) cua tre*.