Perhaps you should try some spelling variations:
cau treo » cau theo, cau tren, cau triet
danh hai » dang hai, lanh hai, manh hai
cam thuc » nam thuc, cam thu, can thuc
hieu van » hieu va, thien van, lieu va
ly nang » ky nang, ly hang, ly vang
cao hoi » cau hoi, co hoi, cao hoc
vu sach » vu bach, vu khach
va danh » va dinh, va dan, va hanh
hai cau » hai chau, hai chu, hai hau
su sach » so sach

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