Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cau thuc » cau truc, cuu thuc, can thuc
cau tren » cu tren, dau tren, ca tren
su sach » vu sach
so sach » so sanh, bo sach, co sach
nang ma » tang ma, sang ma, nang cao
van cau » van dau, van hau, van chat
thuc va » thuc vat, thuc dan, thuc day
dan hai » doan hai, dang hai, dan khai
hai cau » hai chau, hai chu, hai hau
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa
va dan » ca dan, va dao, va dau

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