Perhaps you should try some spelling variations:
cau triet » cau trieu, su triet, cua triet
lam truc » lam truoc, nam truc, lam thuoc
cau treo » cau theo, cau tren, cau trieu
dang hai » dang khai, hang hai, dung hai
hieu van » hieu va, thien van, lieu va
va dang » van dang, va nang, va lang
truc va » thuc va, thuc vat, trung va
su sach » so sach, vu sach
nang ma » tang ma, sang ma, mang may
van lam » van nam
sach v » sach va, sach y, sach 2

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