Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
danh hai » dang hai, lanh hai, manh hai
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, thien van, lieu va
hai cau » hai chau, hai chu, hai hau
va danh » va dinh, va dan, va hanh
thuc va » thuc vat, thuc dan, thuc day
van cam » van nam, van lam, van cau
sach ly » sach lo, sach ty, sach hay
mai hoi » mai khoi, dai hoi, lai hoi
ma hoi » xa hoi, ma hoa, me hoi

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) or (mai 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 ly) OR (sach y)) nang ((ma hoi) OR (mai hoi)). hieu van cam thuc va danh hai cau tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ly) OR (sach y)) nang ((ma hoi) or (mai hoi)). hieu van cam thuc va danh hai cau tren".
• Adding a wildcard symbol may retrieve word variants: su ((sach ly) OR (sach y)) nang ((ma hoi) or (mai hoi)). hieu van cam thuc va danh hai cau tren*.