Perhaps you should try some spelling variations:
cau treo » cau theo, cau tren, cau triet
doan hai » doanh tai, hoang hai, doan va
hieu van » hieu va, thien van, lieu va
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
sach ly » sach y, sach lo, sach ty
thuc va » thuc vat, thuc dan, thuc day
dan hai » dang hai, dan khai, van hai
so sach » so sanh, bo sach, co 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: so sach ly ((nang ma) or (sang ma)) hoi. hieu van am thuc va ((dan hai) OR (doan hai)) cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ly ((nang ma) OR (sang ma)) hoi. hieu van am thuc va ((dan hai) OR (doan hai)) cau treo.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ly ((nang ma) or (sang ma)) hoi. hieu van am thuc va ((dan hai) OR (doan hai)) cau treo".
• Adding a wildcard symbol may retrieve word variants: so sach ly ((nang ma) or (sang ma)) hoi. hieu van am thuc va ((dan hai) OR (doan hai)) cau treo*.