Perhaps you should try some spelling variations:
hau treo » cau treo, cau theo, dau tren
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
nang ma » tang ma, sang ma, nang cao
vu sach » vu bach, vu khach
va danh » va dinh, va dan, va hanh
hai hau » hai chau, dai hau, hai hai
su sach » so sach
ma hoi » mai hoi, xa hoi, ma hoa

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