Perhaps you should try some spelling variations:
sach nuoc » sach duoc, cac nuoc, bach tuoc
cau treo » cau theo, cau tren, cau triet
hanh tai » thanh tai, hang tai, han tai
cua tre » cua te, cuu tre, cua triet
va hanh » van hanh, va thanh, va danh
su sach » vu sach
hieu va » lieu va, hieu qua
so sach » so sanh, bo sach, co sach
va sach » van sach, va cach, a sach
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) OR (so sach)) ky nang x hoi. hieu va sach nuoc va hanh tai ((cua tre) or (cau treo))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ky nang x hoi. hieu va sach nuoc va hanh tai ((cua tre) OR (cau treo)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) ky nang x hoi. hieu va sach nuoc va hanh tai ((cua tre) or (cau treo))".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (so sach)) ky nang x hoi. hieu va sach nuoc va hanh tai ((cua tre) or (cau treo))*.