Perhaps you should try some spelling variations:
ve triet » va trien, su triet
cam thuc » am thuc, nam thuc, cam thu
su viet » so viet
hanh va » hang va, hanh vi
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
dai hoi » dai hoc, dai hai, dai moi
lai hoi » lai hoa, lai roi, mai hoi
ve cam » ve cham, ve cac, va cam

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 ky nang ((lai hoi) OR (dai hoi)). hieu ve cam thuc va hanh va ((su viet) OR (ve triet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ky nang ((lai hoi) OR (dai hoi)). hieu ve cam thuc va hanh va ((su viet) or (ve triet))~".
• Adding a wildcard symbol may retrieve word variants: so sach ky nang ((lai hoi) OR (dai hoi)). hieu ve cam thuc va hanh va ((su viet) or (ve triet))*.