Perhaps you should try some spelling variations:
va thanh » ban thanh, va tinh, le thanh
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
tang ma » mang may, tang van
lang xa » lang ha, dang xay, lang van
qua cam » qua cham, qua cac, qua ca
cam duc » cam xuc, cao duc, pham duc
tai cua » thai cua, tai cuc, tri cua
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: tu sach ty ((tang ma) or (lang xa)) hoi. hieu qua cam duc ((va thanh) OR (gia thanh)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((tang ma) OR (lang xa)) hoi. hieu qua cam duc ((va thanh) OR (gia thanh)) tai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((tang ma) or (lang xa)) hoi. hieu qua cam duc ((va thanh) OR (gia thanh)) tai cua tre*".