Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, te sach, tu cach
cam duc » cam xuc, cao duc, pham duc
hai cua » thai cua, dai cua, hoi cua
lai cua » dai cua, lai chau, thai cua
duc van » duc va, duc tan, duc manh
van cam » van nam, van lam, van cau
su sach » so sach, vu sach
nang o » nang co, nang ho, nang ro
o hoi » co hoi, o hoc, o hai

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (su sach)) ky nang o hoi. hieu van cam duc van hanh ((lai cua) OR (hai cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ky nang o hoi. hieu van cam duc van hanh ((lai cua) OR (hai cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ky nang o hoi. hieu van cam duc van hanh ((lai cua) OR (hai cua)) te".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang o hoi. hieu van cam duc van hanh ((lai cua) OR (hai cua)) te*.