Perhaps you should try some spelling variations:
hai chau » lai chau, ha chau, hat chau
hieu van » hieu va, thien van, lieu va
cam thuc » am thuc, nam thuc, cam thu
van cam » van nam, van lam, van cau
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
hai cau » hai chu, hai hau, hoi cau
su sach » so sach, vu sach
ma hoi » mai hoi, ma hoa, me hoi

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