Perhaps you should try some spelling variations:
cau treo » cau theo, cau tren, cau triet
day manh » van manh, duc manh, ha manh
day danh » dai danh, dao danh, day dan
hieu van » hieu va, thien van, lieu va
sang ma » tang ma, sang tao, mang may
sach ly » sach y, sach lo, sach ty
nang ma » tang ma, nang cao, mang may
hai cau » hai chau, hai chu, hai hau
su sach » so sach, vu sach
van am » van nam, van lam, van dam

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 ly ((nang ma) or (sang ma)) hoi. hieu van am thuc ((day danh) OR (day manh)) hai cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ly ((nang ma) OR (sang ma)) hoi. hieu van am thuc ((day danh) OR (day manh)) hai cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ly ((nang ma) or (sang ma)) hoi. hieu van am thuc ((day danh) OR (day manh)) hai cau treo".
• Adding a wildcard symbol may retrieve word variants: su sach ly ((nang ma) or (sang ma)) hoi. hieu van am thuc ((day danh) OR (day manh)) hai cau treo*.