Perhaps you should try some spelling variations:
thien van » thi van
cau treo » cau theo, cau tren, cau triet
dang hai » dang khai, hang hai, dung hai
hieu van » hieu va, lieu va, hieu ve
cam thuc » am thuc, nam thuc, cam thu
hai cau » hai chau, hai chu, hai hau
va dang » van dang, va nang, va lang
thuc va » thuc vat, thuc dan, thuc day
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
ly nang » ky nang, ly hang, ly vang
ma hoi » mai hoi, xa hoi, ma hoa
bach » cach, bac

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