Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
danh dau » lanh dao, hang dau, danh tu
danh dai » danh di, danh sai, vanh dai
ve pham » vi pham, v pham, ve phan
hieu ve » hieu va, hieu van
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
ma hoi » mai hoi, xa hoi, ma hoa
cua te » cua tu

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) or (toc sach)) ky sang ma hoi. hieu ve pham duc va ((danh dai) OR (danh dau)) cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky sang ma hoi. hieu ve pham duc va ((danh dai) OR (danh dau)) cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ky sang ma hoi. hieu ve pham duc va ((danh dai) OR (danh dau)) cua te".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky sang ma hoi. hieu ve pham duc va ((danh dai) OR (danh dau)) cua te*.