Perhaps you should try some spelling variations:
trinh tai » trinh toan, trinh tu, trinh han
dang van » hoang van, hang va
tu sach » thu sach, su sach, te sach
sach tu » sach thu, cach tu, sach ty
tai cua » thai cua, tai cuc, tri cua
qua cac » cua cac
lang xa » lang ha, dang xay, lang van
cua tre » cua te, cuu tre, cua triet
xuc va » duc va, tuc va, xac va
luc va » duc va, tuc va, loc va

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach tu ((dang van) or (lang xa)) hoi. hieu qua cac ((xuc va) or (luc va)) trinh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach tu ((dang van) OR (lang xa)) hoi. hieu qua cac ((xuc va) OR (luc va)) trinh tai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach tu ((dang van) or (lang xa)) hoi. hieu qua cac ((xuc va) or (luc va)) trinh tai cua tre*.