Perhaps you should try some spelling variations:
cau treo » cau theo, cau tren, cau triet
cam thuc » am thuc, cam thu, can thuc
manh hai » lanh hai, minh hai, thanh hai
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
hai cau » hai chau, hai chu, hai hau
va manh » van manh, va danh, va hanh
so sach » so sanh, bo sach, co sach
ly vang » ly hang, ly van, ly quang
ly nang » ky nang, ly hang, ly quang

You may be able to get more results by adjusting your search query.

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