Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
hai chau » lai chau, ha chau, hat chau
day danh » day manh, dai danh, dao danh
thuc day » thuc dan, thuc vat
hieu van » hieu va, thien van, lieu va
hai cau » hai chu, hai hau, hoi cau
sach ly » sach lo, sach ty, sach hay
nang ma » tang ma, sang ma, nang cao
van cam » van nam, van lam, van cau
ma hoi » mai hoi, xa hoi, ma hoa

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