Perhaps you should try some spelling variations:
danh tai » doanh tai, dinh tai, hanh tai
thu sach » tu sach, thuat sach, thuoc sach
sang mai » sang ma, sang tai, lang mai
tu cach » tu cac
va danh » va dinh, va dan, va hanh
cac toc » cac toi, cac nuoc, cac thoi
cac tuc » cac tu, cac tac, cac nuoc
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
ky sang » ky nang, ky dang, ky tang
cuc tre » duc tre, cua tre, cuu tre

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

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