Perhaps you should try some spelling variations:
sang mai » sang ma, sang tai, lang mai
danh doi » danh di, thanh doi, dung doi
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
ky sang » ky nang, ky dang, ky tang
mai hoi » mai khoi, dai hoi, lai hoi
hieu ve » hieu van
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac tac
xa danh » va danh, dia danh, nam danh
doi cua » dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky sang mai hoi. ((hieu ve) or (hieu va)) cac tuc xa danh doi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky sang mai hoi. ((hieu ve) OR (hieu va)) cac tuc xa danh doi cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ky sang mai hoi. ((hieu ve) or (hieu va)) cac tuc xa danh doi cua tre*.