Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cam thuc » am thuc, nam thuc, cam thu
danh hai » dang hai, lanh hai, manh hai
cau tren » cu tren, dau tren, ca tren
su sach » so sach, vu sach
nang ma » tang ma, sang ma, mang may
van cam » van nam, van lam, van cau
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
hai cau » hai chau, hai chu, hai hau
sach v » sach va, sach y, sach 2

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