Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
cam thuc » nam thuc, cam thu, can thuc
hieu van » hieu va, thien van, lieu va
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
sach ly » sach y, sach lo, sach hay
dan hai » doan hai, dang hai, dan khai
hai cau » hai chau, hai chu, hai hau
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 ly) or (sach ty)) nang ma hoi. hieu van ((cam thuc) or (am thuc)) va dan hai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ly) OR (sach ty)) nang ma hoi. hieu van ((cam thuc) OR (am thuc)) va dan hai cau tren.
• Adding a wildcard symbol may retrieve word variants: su ((sach ly) or (sach ty)) nang ma hoi. hieu van ((cam thuc) or (am thuc)) va dan hai cau tren*.