Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
chua tre » chua tri, cua tre, chua trieu
hanh sua » hinh su, hanh va, hanh tu
sang dai » sang tai, lang dai, sang mai
va hanh » van hanh, va thanh, va danh
cac toc » cac toi, cac nuoc, cac thoi
cac tuc » cac tu, cac tac, cac nuoc
te sach » toc sach
dai hoi » dai hoc, dai hai, dai moi
ky sang » ky nang, ky dang, ky tang
hieu ve » hieu va, hieu van

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