Perhaps you should try some spelling variations:
trinh viet » ninh viet, trinh vat
dinh viet » ninh viet, danh viet, sinh vien
toc sach » hoc sach, doc sach, thuoc sach
sang mai » sang ma, sang tai, lang mai
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ty sang » ty xang, ty hang, duy sang
ve cac » va cac, vien cac
dac va » duc va, day va, dai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty sang mai hoi. hieu ve cac ((dac va) OR (dat va)) ((dinh viet) or (trinh viet)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty sang mai hoi. hieu ve cac ((dac va) OR (dat va)) ((dinh viet) OR (trinh viet)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty sang mai hoi. hieu ve cac ((dac va) OR (dat va)) ((dinh viet) or (trinh viet)) cua tre*".