Perhaps you should try some spelling variations:
trinh viet » ninh viet, trinh vat
hoc thuoc » hoc thuc, hoc thuong, hoc nuoc
thuoc vat » thuc vat, thuoc va, thuoc bat
trong xa » trong xay, trong ca, trong xu
tinh vi » trinh vi, tinh voi, tinh va
su sach » so sach, vu sach
hieu ve » hieu va, hieu van
tang xa » trang xa, tang ma, lang xa
cua tre » cua te, cuu tre, cua triet
ve hoc » te hoc, va hoc, vi hoc

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 y ((tang xa) or (trong xa)) hoi. hieu ve hoc thuoc vat ((tinh vi) or (trinh viet)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y ((tang xa) OR (trong xa)) hoi. hieu ve hoc thuoc vat ((tinh vi) OR (trinh viet)) cua tre.
• Adding a wildcard symbol may retrieve word variants: su sach y ((tang xa) or (trong xa)) hoi. hieu ve hoc thuoc vat ((tinh vi) or (trinh viet)) cua tre*.