Perhaps you should try some spelling variations:
ninh viet » sinh vien, anh viet
toc sach » hoc sach, doc sach, thuoc sach
viet cuu » viet suu, viet cau, viet chu
sach ty » sach y, sach tu, sach thu
va ninh » van ninh, va kinh, va tinh
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ty sang » ty xang, ty hang, duy sang
cuu tre » cua tre, cau tren, cau treo
ve cac » va cac, vien cac
ma hoi » xa hoi, me hoi, va hoi

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 ((((ma hoi) OR (ma hoa))) or (mai hoi)). hieu ve cac duc va ninh viet cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty sang ((((ma hoi) OR (ma hoa))) OR (mai hoi)). hieu ve cac duc va ninh viet cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty sang ((((ma hoi) OR (ma hoa))) or (mai hoi)). hieu ve cac duc va ninh viet cuu tre*".