Perhaps you should try some spelling variations:
ninh viet » sinh vien, anh viet
dinh viet » danh viet, trinh viet, sinh vien
te sach » toc sach
cac day » cac dan, cac dai, cac cay
sach ty » sach y, sach tu, sach thu
hieu ve » hieu va, hieu van
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
ve cac » va cac, vien cac
co tre » cho tre, co tren, o tre

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ty ((nang ma) or (tang ma)) hoi. hieu ve cac day va ((dinh viet) OR (ninh viet)) co tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ty ((nang ma) OR (tang ma)) hoi. hieu ve cac day va ((dinh viet) OR (ninh viet)) co tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ty ((nang ma) or (tang ma)) hoi. hieu ve cac day va ((dinh viet) OR (ninh viet)) co tre*".