Perhaps you should try some spelling variations:
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, thien van, lieu va
mai hoi » mai khoi, dai hoi, lai hoi
sach ly » sach y, sach lo, sach ty
van cam » van nam, van lam, van cau
ly nang » ky nang, ly hang, ly vang
thuc ca » thuc cua, thuc can, thuc cao
hai cau » hai chau, hai hau, hoi cau
hai chu » hai chau, hoi chu, hai chi
su sach » so sach, vu sach
ma hoi » xa 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 ly nang ((ma hoi) or (mai hoi)). hieu van cam thuc ca dao ((hai cau) or (hai chu)) treo~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ly nang ((ma hoi) OR (mai hoi)). hieu van cam thuc ca dao ((hai cau) OR (hai chu)) treo.
• Adding a wildcard symbol may retrieve word variants: su sach ly nang ((ma hoi) or (mai hoi)). hieu van cam thuc ca dao ((hai cau) or (hai chu)) treo*.