Perhaps you should try some spelling variations:
thuat sac » thuat sach, thuat san, thuat tac
cam duc » cam xuc, cao duc, pham duc
hanh de » hanh ve, hanh kem
hang vi » hang va, hanh vi, hang di
su viet » so viet
sac ky » cac ky, sai ky
co hoi » co hoc, co loi
va cam » va cham, va cac, va cao
o hoi » o hoc, o hai, o hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sac ky nang ((o hoi) OR (co hoi)). lieu va cam duc va ((hanh de) or (hang vi)) su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sac ky nang ((o hoi) OR (co hoi)). lieu va cam duc va ((hanh de) OR (hang vi)) su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sac ky nang ((o hoi) OR (co hoi)). lieu va cam duc va ((hanh de) or (hang vi)) su viet".
• Adding a wildcard symbol may retrieve word variants: thuat sac ky nang ((o hoi) OR (co hoi)). lieu va cam duc va ((hanh de) or (hang vi)) su viet*.