Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
hieu van » hieu va, thien van, lieu va
hang di » hang doi, hang vi, hang dien
hanh de » hanh ve, hanh kem
lam duc » lam duoc, pham duc, nam duoc
van lam » van nam
su viet » so viet
sach ky » sac ky, sach y, sach ty
co hoi » co hoc, co loi
o hoi » o hoc, o hai, o hoa

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: thuat sach ky nang ((o hoi) OR (co hoi)). hieu van lam duc va ((hanh de) OR (hang di)) su viet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ky nang ((o hoi) OR (co hoi)). hieu van lam duc va ((hanh de) or (hang di)) su viet~".
• Adding a wildcard symbol may retrieve word variants: thuat sach ky nang ((o hoi) OR (co hoi)). hieu van lam duc va ((hanh de) or (hang di)) su viet*.