Perhaps you should try some spelling variations:
danh dai » danh dau, danh di, danh sai
hoc sach » hoc sinh, hoc cac, hoc anh
hieu van » hieu va, thien van, lieu va
hieu ve » hieu va
va danh » va dinh, va dan, va hanh
te sach » toc sach
sang ma » tang ma, nang ma, sang tao
ky sang » ky nang, ky dang, ky tang
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa

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