Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
cau treo » cau theo, cau triet, cau trieu
lam thuc » lam thuoc, am thuc, nam thuc
hieu van » hieu va, thien van, lieu va
dan hai » doan hai, dang hai, dan khai
thuc va » thuc vat, thuc dan, thuc day
su sach » so sach
nang ma » tang ma, sang ma, nang cao
ly nang » ky nang, ly hang, ly vang
vu sach » vu bach, vu khach
van lam » van nam
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) or (vu sach)) ly nang ma hoi. hieu van lam thuc va dan hai ((cau treo) OR (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu sach)) ly nang ma hoi. hieu van lam thuc va dan hai ((cau treo) OR (cau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu sach)) ly nang ma hoi. hieu van lam thuc va dan hai ((cau treo) OR (cau tren))".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu sach)) ly nang ma hoi. hieu van lam thuc va dan hai ((cau treo) OR (cau tren))*.