Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cau treo » cau theo, cau tren, cau triet
so sach » so sanh, bo sach, co sach
tang ma » tang van
van cau » van dau, van hau, van chat
truc va » thuc va, thuc vat, trung va
dau hai » dai hai, dau ha, cau hai
hai cau » hai chau, hai chu, hai hau
va dau » va dao

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 y ((((mang may) or (tang ma))) or (nang cao)) hoi. hieu van cau truc va dau hai cau treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((((mang may) OR (tang ma))) OR (nang cao)) hoi. hieu van cau truc va dau hai cau treo.
• Adding a wildcard symbol may retrieve word variants: so sach y ((((mang may) or (tang ma))) or (nang cao)) hoi. hieu van cau truc va dau hai cau treo*.