Perhaps you should try some spelling variations:
cau nuoc » cap nuoc, cac nuoc, dau nuoc
hang hai » hoang hai, hang tai, thanh hai
hanh hai » thanh hai, nhanh hai, hanh tai
hieu van » hieu va, thien van, lieu va
su sach » vu sach
van cau » van dau, van hau, van chat
so sach » so sanh, bo sach, co sach
cuu tre » cua tre, cau tren, cau treo
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 van cau nuoc va ((hanh hai) or (hang hai)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ky nang x hoi. hieu van cau nuoc va ((hanh hai) OR (hang hai)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) ky nang x hoi. hieu van cau nuoc va ((hanh hai) or (hang hai)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (so sach)) ky nang x hoi. hieu van cau nuoc va ((hanh hai) or (hang hai)) cuu tre*.